//将NSData转化为NSString        NSString* str = [[NSString alloc] initWithData:response encoding:NSUTF8StringEncoding];//将NSString 转化为NSData(NSString.h)- (NSData *)dataUsingEncoding:(NSStringEncoding)encoding;   //载一个字符串中删除一个字符或字符串[_display deleteCharactersInRange:NSMakeRange(index_of_char_to_remove, 1)];数学转换为字符串NSString *returnStr;returnStr = [[NSNumber numberWithInt:row] stringValue];     NSString       *******************************************************************************************/      //一、NSString          /*----------------创建字符串的方法----------------*/            //1、创建常量字符串。      NSString *astring = @"This is a String!";                  //2、创建空字符串，给予赋值。            NSString *astring = [[NSString alloc] init];      astring = @"This is a String!";      [astring release];      NSLog(@"astring:%@",astring);                        //3、在以上方法中，提升速度:initWithString方法            NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];      NSLog(@"astring:%@",astring);      [astring release];                        //4、用标准c创建字符串:initWithCString方法            char *Cstring = "This is a String!";      NSString *astring = [[NSString alloc] initWithCString:Cstring];      NSLog(@"astring:%@",astring);      [astring release];                        //5、创建格式化字符串:占位符（由一个%加一个字符组成）            int i = 1;      int j = 2;      NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"%d.This is %i string!",i,j]];      NSLog(@"astring:%@",astring);      [astring release];                        //6、创建临时字符串            NSString *astring;      astring = [NSString stringWithCString:"This is a temporary string"];      NSLog(@"astring:%@",astring);                              /*----------------从文件读取字符串:initWithContentsOfFile方法----------------*/                NSString *path = @"astring.text";      NSString *astring = [[NSString alloc] initWithContentsOfFile:path];      NSLog(@"astring:%@",astring);      [astring release];                  /*----------------写字符串到文件:writeToFile方法----------------*/                      NSString *astring = [[NSString alloc] initWithString:@"This is a String!"];      NSLog(@"astring:%@",astring);      NSString *path = @"astring.text";          [astring writeToFile: path atomically: YES];      [astring release];                                  /*----------------比较两个字符串----------------*/                    //用C比较:strcmp函数            char string1[] = "string!";      char string2[] = "string!";      if(strcmp(string1, string2) = = 0)      {          NSLog(@"1");      }                        //isEqualToString方法          NSString *astring01 = @"This is a String!";      NSString *astring02 = @"This is a String!";      BOOL result = [astring01 isEqualToString:astring02];      NSLog(@"result:%d",result);                              //compare方法(comparer返回的三种值)          NSString *astring01 = @"This is a String!";      NSString *astring02 = @"This is a String!";          BOOL result = [astring01 compare:astring02] = = NSOrderedSame;          NSLog(@"result:%d",result);          //NSOrderedSame判断两者内容是否相同                              NSString *astring01 = @"This is a String!";      NSString *astring02 = @"this is a String!";      BOOL result = [astring01 compare:astring02] = = NSOrderedAscending;          NSLog(@"result:%d",result);      //NSOrderedAscending判断两对象值的大小(按字母顺序进行比较，astring02大于astring01为真)                        NSString *astring01 = @"this is a String!";      NSString *astring02 = @"This is a String!";      BOOL result = [astring01 compare:astring02] = = NSOrderedDescending;          NSLog(@"result:%d",result);           //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)                        //不考虑大小写比较字符串1      NSString *astring01 = @"this is a String!";      NSString *astring02 = @"This is a String!";      BOOL result = [astring01 caseInsensitiveCompare:astring02] = = NSOrderedSame;          NSLog(@"result:%d",result);           //NSOrderedDescending判断两对象值的大小(按字母顺序进行比较，astring02小于astring01为真)                        //不考虑大小写比较字符串2      NSString *astring01 = @"this is a String!";      NSString *astring02 = @"This is a String!";      BOOL result = [astring01 compare:astring02                              options:NSCaseInsensitiveSearch | NSNumericSearch] = = NSOrderedSame;          NSLog(@"result:%d",result);                 //NSCaseInsensitiveSearch:不区分大小写比较 NSLiteralSearch:进行完全比较，区分大小写 NSNumericSearch:比较字符串的字符个数，而不是字符值。                  /*----------------改变字符串的大小写----------------*/                NSString *string1 = @"A String";       NSString *string2 = @"String";       NSLog(@"string1:%@",[string1 uppercaseString]);//大写      NSLog(@"string2:%@",[string2 lowercaseString]);//小写      NSLog(@"string2:%@",[string2 capitalizedString]);//首字母大小                  /*----------------在串中搜索子串----------------*/                    NSString *string1 = @"This is a string";      NSString *string2 = @"string";      NSRange range = [string1 rangeOfString:string2];      int location = range.location;      int leight = range.length;      NSString *astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%i,Leight:%i",location,leight]];      NSLog(@"astring:%@",astring);      [astring release];                  /*----------------抽取子串 ----------------*/                    //-substringToIndex: 从字符串的开头一直截取到指定的位置，但不包括该位置的字符      NSString *string1 = @"This is a string";      NSString *string2 = [string1 substringToIndex:3];      NSLog(@"string2:%@",string2);                              //-substringFromIndex: 以指定位置开始（包括指定位置的字符），并包括之后的全部字符      NSString *string1 = @"This is a string";      NSString *string2 = [string1 substringFromIndex:3];      NSLog(@"string2:%@",string2);                              //-substringWithRange: //按照所给出的位置，长度，任意地从字符串中截取子串      NSString *string1 = @"This is a string";      NSString *string2 = [string1 substringWithRange:NSMakeRange(0, 4)];      NSLog(@"string2:%@",string2);                  //扩展路径            NSString *Path = @"~/NSData.txt";      NSString *absolutePath = [Path stringByExpandingTildeInPath];      NSLog(@"absolutePath:%@",absolutePath);      NSLog(@"Path:%@",[absolutePath stringByAbbreviatingWithTildeInPath]);                        //文件扩展名      NSString *Path = @"~/NSData.txt";      NSLog(@"Extension:%@",[Path pathExtension]);                              /*******************************************************************************************       NSMutableString       *******************************************************************************************/                /*---------------给字符串分配容量----------------*/      //stringWithCapacity:      NSMutableString *String;      String = [NSMutableString stringWithCapacity:40];                  /*---------------在已有字符串后面添加字符----------------*/                //appendString: and appendFormat:            NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];      //[String1 appendString:@", I will be adding some character"];      [String1 appendFormat:[NSString stringWithFormat:@", I will be adding some character"]];      NSLog(@"String1:%@",String1);      */                  /*--------在已有字符串中按照所给出范围和长度删除字符------*/          /*       //deleteCharactersInRange:       NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];       [String1 deleteCharactersInRange:NSMakeRange(0, 5)];       NSLog(@"String1:%@",String1);                         /*--------在已有字符串后面在所指定的位置中插入给出的字符串------*/            //-insertString: atIndex:      NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];      [String1 insertString:@"Hi! " atIndex:0];      NSLog(@"String1:%@",String1);                        /*--------将已有的空符串换成其它的字符串------*/            //-setString:      NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];      [String1 setString:@"Hello Word!"];      NSLog(@"String1:%@",String1);                        /*--------按照所给出的范围，和字符串替换的原有的字符------*/            //-setString:      NSMutableString *String1 = [[NSMutableString alloc] initWithString:@"This is a NSMutableString"];      [String1 replaceCharactersInRange:NSMakeRange(0, 4) withString:@"That"];      NSLog(@"String1:%@",String1);                        /*-------------判断字符串内是否还包含别的字符串(前缀，后缀)-------------*/      //01：检查字符串是否以另一个字符串开头- (BOOL) hasPrefix: (NSString *) aString;      NSString *String1 = @"NSStringInformation.txt";      [String1 hasPrefix:@"NSString"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");      [String1 hasSuffix:@".txt"] = = 1 ?  NSLog(@"YES") : NSLog(@"NO");            //02：查找字符串某处是否包含其它字符串 - (NSRange) rangeOfString: (NSString *) aString，这一点前面在串中搜索子串用到过;                        /*******************************************************************************************       NSArray       *******************************************************************************************/            /*---------------------------创建数组------------------------------*/      //NSArray *array = [[NSArray alloc] initWithObjects:      @"One",@"Two",@"Three",@"Four",nil];            self.dataArray = array;      [array release];            //- (unsigned) Count;数组所包含对象个数；      NSLog(@"self.dataArray cound:%d",[self.dataArray count]);            //- (id) objectAtIndex: (unsigned int) index;获取指定索引处的对象;      NSLog(@"self.dataArray cound 2:%@",[self.dataArray objectAtIndex:2]);                  /*--------------------------从一个数组拷贝数据到另一数组(可变数级)----------------------------*/                //arrayWithArray:      //NSArray *array1 = [[NSArray alloc] init];      NSMutableArray *MutableArray = [[NSMutableArray alloc] init];      NSArray *array = [NSArray arrayWithObjects:                        @"a",@"b",@"c",nil];      NSLog(@"array:%@",array);      MutableArray = [NSMutableArray arrayWithArray:array];      NSLog(@"MutableArray:%@",MutableArray);            array1 = [NSArray arrayWithArray:array];      NSLog(@"array1:%@",array1);                  //Copy            //id obj;      NSMutableArray *newArray = [[NSMutableArray alloc] init];      NSArray *oldArray = [NSArray arrayWithObjects:                           @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];            NSLog(@"oldArray:%@",oldArray);      for(int i = 0; i < [oldArray count]; i++)      {                  obj = [[oldArray objectAtIndex:i] copy];          [newArray addObject: obj];      }      //           NSLog(@"newArray:%@", newArray);      [newArray release];                  //快速枚举            //NSMutableArray *newArray = [[NSMutableArray alloc] init];      NSArray *oldArray = [NSArray arrayWithObjects:                           @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];          NSLog(@"oldArray:%@",oldArray);            for(id obj in oldArray)      {          [newArray addObject: obj];      }      //           NSLog(@"newArray:%@", newArray);      [newArray release];                      //Deep copy            //NSMutableArray *newArray = [[NSMutableArray alloc] init];      NSArray *oldArray = [NSArray arrayWithObjects:                           @"a",@"b",@"c",@"d",@"e",@"f",@"g",@"h",nil];          NSLog(@"oldArray:%@",oldArray);          newArray = (NSMutableArray*)CFPropertyListCreateDeepCopy(kCFAllocatorDefault, (CFPropertyListRef)oldArray, kCFPropertyListMutableContainers);      NSLog(@"newArray:%@", newArray);      [newArray release];                      //Copy and sort            //NSMutableArray *newArray = [[NSMutableArray alloc] init];      NSArray *oldArray = [NSArray arrayWithObjects:                           @"b",@"a",@"e",@"d",@"c",@"f",@"h",@"g",nil];          NSLog(@"oldArray:%@",oldArray);      NSEnumerator *enumerator;      enumerator = [oldArray objectEnumerator];      id obj;      while(obj = [enumerator nextObject])      {          [newArray addObject: obj];      }      [newArray sortUsingSelector:@selector(compare:)];      NSLog(@"newArray:%@", newArray);      [newArray release];                        /*---------------------------切分数组------------------------------*/            //从字符串分割到数组－ componentsSeparatedByString:      NSString *string = [[NSString alloc] initWithString:@"One,Two,Three,Four"];      NSLog(@"string:%@",string);          NSArray *array = [string componentsSeparatedByString:@","];      NSLog(@"array:%@",array);      [string release];                  //从数组合并元素到字符串- componentsJoinedByString:      NSArray *array = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",@"Four",nil];      NSString *string = [array componentsJoinedByString:@","];      NSLog(@"string:%@",string);                        /*******************************************************************************************       NSMutableArray       *******************************************************************************************/      /*---------------给数组分配容量----------------*/      //NSArray *array;      array = [NSMutableArray arrayWithCapacity:20];                        /*--------------在数组末尾添加对象----------------*/      //- (void) addObject: (id) anObject;      //NSMutableArray *array = [NSMutableArray arrayWithObjects:      @"One",@"Two",@"Three",nil];      [array addObject:@"Four"];      NSLog(@"array:%@",array);                        /*--------------删除数组中指定索引处对象----------------*/          //-(void) removeObjectAtIndex: (unsigned) index;          //NSMutableArray *array = [NSMutableArray arrayWithObjects:      @"One",@"Two",@"Three",nil];      [array removeObjectAtIndex:1];      NSLog(@"array:%@",array);                        /*-------------数组枚举---------------*/          //- (NSEnumerator *)objectEnumerator;从前向后      //NSMutableArray *array = [NSMutableArray arrayWithObjects:      @"One",@"Two",@"Three",nil];      NSEnumerator *enumerator;      enumerator = [array objectEnumerator];            id thingie;      while (thingie = [enumerator nextObject]) {          NSLog(@"thingie:%@",thingie);      }                  //- (NSEnumerator *)reverseObjectEnumerator;从后向前      //NSMutableArray *array = [NSMutableArray arrayWithObjects:      @"One",@"Two",@"Three",nil];      NSEnumerator *enumerator;      enumerator = [array reverseObjectEnumerator];            id object;      while (object = [enumerator nextObject]) {          NSLog(@"object:%@",object);      }                  //快速枚举      //NSMutableArray *array = [NSMutableArray arrayWithObjects:      @"One",@"Two",@"Three",nil];      for(NSString *string in array)      {          NSLog(@"string:%@",string);      }                        /*******************************************************************************************       NSDictionary       *******************************************************************************************/            /*------------------------------------创建字典------------------------------------*/      //- (id) initWithObjectsAndKeys;            //NSDictionary *dictionary = [[NSDictionary alloc] initWithObjectsAndKeys:@"One",@"1",@"Two",@"2",@"Three",@"3",nil];      NSString *string = [dictionary objectForKey:@"One"];      NSLog(@"string:%@",string);      NSLog(@"dictionary:%@",dictionary);      [dictionary release];                  /*******************************************************************************************       NSMutableDictionary       *******************************************************************************************/            /*------------------------------------创建可变字典------------------------------------*/          //创建      NSMutableDictionary *dictionary = [NSMutableDictionary dictionary];            //添加字典      [dictionary setObject:@"One" forKey:@"1"];      [dictionary setObject:@"Two" forKey:@"2"];      [dictionary setObject:@"Three" forKey:@"3"];      [dictionary setObject:@"Four" forKey:@"4"];      NSLog(@"dictionary:%@",dictionary);            //删除指定的字典      [dictionary removeObjectForKey:@"3"];      NSLog(@"dictionary:%@",dictionary);                  /*******************************************************************************************       NSValue（对任何对象进行包装）       *******************************************************************************************/            /*--------------------------------将NSRect放入NSArray中------------------------------------*/          //将NSRect放入NSArray中      NSMutableArray *array = [[NSMutableArray alloc] init];      NSValue *value;      CGRect rect = CGRectMake(0, 0, 320, 480);          value = [NSValue valueWithBytes:&rect objCType:@encode(CGRect)];      [array addObject:value];      NSLog(@"array:%@",array);            //从Array中提取      value = http://www.mamicode.com/[array objectAtIndex:0];      [value getValue:&rect];      NSLog(@"value:%@",value);                  /*******************************************************************************************       从目录搜索扩展名为jpg的文件       *******************************************************************************************/            //NSFileManager *fileManager = [NSFileManager defaultManager];      NSString *home;      home = @"../Users/";            NSDirectoryEnumerator *direnum;      direnum = [fileManager enumeratorAtPath: home];            NSMutableArray *files = [[NSMutableArray alloc] init];            //枚举      NSString *filename;      while (filename = [direnum nextObject]) {          if([[filename pathExtension] hasSuffix:@"jpg"]){              [files addObject:filename];          }      }            //快速枚举      //for(NSString *filename in direnum)      //{      //    if([[filename pathExtension] isEqualToString:@"jpg"]){      //        [files addObject:filename];      //    }      //}      NSLog(@"files:%@",files);            //枚举      NSEnumerator *filenum;      filenum = [files objectEnumerator];      while (filename = [filenum nextObject]) {          NSLog(@"filename:%@",filename);      }            //快速枚举      //for(id object in files)      //{      //    NSLog(@"object:%@",object);      //}      #import <Foundation/Foundation.h>            int main (int argc, const char * argv[]) {          NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];          //创建字符串          NSString *height;          /**类方法：         +(id) stringWithFormat: (NSString *) format,...         通过格式字符串和参数来创建NSString         省略号（。。。）：可以接受多个以逗号分割的参数。         这声明方法时添加加号（＋），那么这个方法为类方法，不需要创建实例就可以调用，通常用于创建心的实例，我们称用来创建新对象的类方法为工厂方法。         －－－－－－－－－－－－－－－－－－－         objective－c运行时生成一个类的时候，它会创建一个代表该类的类对象。类对象包含了指向超类的指针，类名，和指向类方法列表的指针。类对象还包含一个long型数据，为新创建的类实例对象指定大小（以字节为单位）                   类方法可以用来访问全局数据。                   实例方法要用前导减号（－）来开始声明                   */                    height=[NSString stringWithFormat:@"you heigh is %d feet,%d inches",5,11];          NSLog(height);          //length 返回字符串中字符的个数。－（unsigned int) length;          if([height length]>5){              NSLog(@"height length ------");          }                    //字符串比较          /**         isEqualToString :可以用来比较接收方和当作参数传递来的字符串的内容是否相同，返回yes和no         */          NSString *thing1=@"hello";          NSString *thing2=[[NSString alloc] initWithString:@"hello"];          if([thing1 isEqualToString:thing2]){              NSLog(@"they are same");              }          /**         ==:只判断指针数值，而不是它们所指向的内容         */          if(thing1==thing2){              NSLog(@"== same");          }                    /*         compare:比较两个字符串。区分大小写         compare将接收对象和传递来的字符串逐个字符的进行比较，它返回一个NSComparisonResult(枚举类型)来显示结果。         typedef enum _NSComparisonResult{         NSOrderedAscending=-1;         NSOrderedsame;         NSOrderedDescending;         } NSComparisonResult;         */          [thing1 compare:thing2];          if(NSOrderedSame==[thing1 compare:thing2]){              NSLog(@"compare same");           }                    //compare：options:           /***         -(NSComparisonResult) compare:(NSString *) string           options:(unsinged) mask;                   options 是一个位掩码，可以使用|添加选项标记         选项：         NSCaseInsensitiveSearch:不区分大小写字符         NSLiteralSearch:进行完全比较，区分大小写         NSNumbericSearch:比较字符串的字符个数，而不是字符值         */          if([thing1 compare:thing2 options:NSCaseInsensitiveSearch|               NSNumericSearch]==NSOrderedSame){              NSLog(@"they match");          }                    /**         以某个字符串开始或结尾         -(BOOL) hasPrefix:(NSString *) aString;         -(BOOL) hasSuffix:(NSString *) aString;         */          NSString *fileName=@"aabbbcc";          if([fileName hasPrefix:@"aa"]){              NSLog(@"begin with aa");          }                    if([fileName hasSuffix:@"cc"]){              NSLog(@"end with cc");          }                    //NSMutableString 可变字符串          //SString 是不可变的，一旦NSString 被创建了，我们就不能改变它。                    //+(id) stringWithCapacity:(unsinged) capacity; capacity:是给NSMutableString的一个建议，字符串的大小并不局限于所提供的大小，这个容量仅是个最优值。                    NSMutableString *str=[NSMutableString stringWithCapacity:40];          [str appendFormat:@"sdfsdf%d",5];          [str appendString:@"ssssssss"];          NSLog(str);                    //删除字符串          //-(void) deleteCharactersInRange:(NSRange) range;                    NSMutableString *ms;          ms=[NSMutableString stringWithCapacity:50];          [ms appendString:@"aabbccdd"];          NSRange range;          range=[ms rangeOfString:@"cc"];          [ms deleteCharactersInRange:range];          NSLog(ms);                    //与实例方法一样，继承对类方法也同样适用                    //------------------集合－－－－－－－－－－－－－－          //NSArray ,NSDictionary          /**         NSArray 是一个cocoa类，用来存储对象的有序列表。        NSArray有两个限制：1，它只能存储objective－c的对象，而不能存储c语言中的基本数据类型如int，float，enum，struct，或者nsarray中的随机指针。2，不能这nsarray中存储nil                   类方法：         arrayWithObjects:创建一个新的nsarray。发送一个以逗号分割的对象列表，这列表结尾添加nil代表列表结束，（这就是不能这nsarray中存储nil的原因）                   */          NSArray *array=[NSArray arrayWithObjects:@"aa",@"bb",@"cc",nil];                    //-(unsigned) count; 取得包含对象的个数          //-(id) objectAtIndex:(unsigned int) index; 取得索引位置的对象                    int i;          for (i=0; i<[array count]; i++) {              NSLog(@"index %d has %@",i,[array objectAtIndex:i]);          }                    //------------切分数组          //-componentsSeparatedByString:          NSString *ns=@"sdf,dsfs,dfd,fdf,df,dd";          NSArray *comArr=[ns componentsSeparatedByString:@","];          for(int i=0;i<[comArr count];i++){              NSLog(@"componentsSeparatedByString===%@",[comArr objectAtIndex:i]);          }                    //componentJoinedByString: 合并nsarray中的元素来创建字符串          NSString *joinedStr=[comArr componentsJoinedByString:@"-->"];          NSLog(@"joined---= %@",joinedStr);                    //可变数组          NSMutableArray *mutableArr=[NSMutableArray arrayWithCapacity:40];          [mutableArr addObject:@"aa"];          [mutableArr addObject:@"bb"];          [mutableArr addObject:@"cc"];          [mutableArr addObject:@"dd"];                    for(int i=0;i<[mutableArr count];i++){              NSLog(@"mutableArr==%@",[mutableArr objectAtIndex:i]);          }                    //-----  -(void) removeObjectAtIndex:(unsinged) index; 删除指定索引的对象,          //删除一个对象之后，数组中并没有留下漏洞，被删除对象后面的数组元素的哦被前移来填补空缺          [mutableArr removeObjectAtIndex:2];          for(int i=0;i<[mutableArr count];i++){              NSLog(@"removeObjectAtIndex == %@",[mutableArr objectAtIndex:i]);          }                    //枚举          //NSEnumerator ,它是cocoa用来描述这种集合迭代运输的方法          //-(NSEnumerator *) objectEnumerator;          NSEnumerator *enumerator=[mutableArr objectEnumerator];          id thingie;          while(thingie=[enumerator nextObject]){              NSLog(@"i found %@",thingie);          }                    //快速枚举          for(NSString *string in mutableArr){              NSLog(@"for in == %@",string);          }                    //NSDictionary 字典          /*         NSDictionary 是在给定的关键字（通常是一个NSString字符串）下存储一个数值（可以是任何类型的对象）。然后你可以用这个关键字来查找相应的数值。         NSDictionary 是键查询的优化存储方式。它可以立即找出要查询的数据，而不需要遍历整个数组进行查找。                   ＋（id) dictionaryWithObjectAndKeys:(id) firstObject,....;         该方法接收对象和关键字交替出现的系列，以nil值作为终止符号。         **/          NSDictionary *dic=[NSDictionary dictionaryWithObjectsAndKeys:@"aaa",@"a",@"bbb",@"b",nil];          NSString *dicStr=[dic objectForKey:@"a"];          if([dicStr isEqualToString:@"aaa"]){              NSLog(@"------------00000000000000000");          }                    //可变字典          NSMutableDictionary *mutableDic=[NSMutableDictionary dictionaryWithCapacity:50];          [mutableDic setObject:@"1111" forKey:@"1"];          [mutableDic setObject:@"222" forKey:@"2"];                    //删除 -(void) removeObjectForKe:(id) key;          [mutableDic removeObjectForKey:@"2"];                    NSArray *keyArr=[mutableDic allKeys];          for(NSString *str in keyArr){              NSLog(@"key== %@",str);              NSLog(@"value=http://www.mamicode.com/= %@",[mutableDic objectForKey:str]);          }                              //各种数值，NSNumber NSValue          /*         cocoa 提供了NSNumber类来包装基本数据类型         +(NSNumber *) numberWithChar:(char) value;         +(NSNumber *) numberWithInt:(int) value;         +(NSNumber *) numberWithFloat:(float) value;         +(NSNumber *) numberWthiBool:(BOOL) value;                   -(char) charValue;         -(int) intVlaue;         -(float) floatValue;         -(BOOL) boolValue;         -(NSString *) stringValue;                             **/          NSNumber *number;          number=[NSNumber numberWithInt:3];          [mutableDic setObject:number forKey:@"int"];                    int num=[[mutableDic objectForKey:@"int"] intValue];          NSLog(@"int object value=http://www.mamicode.com/= %d",num);                              //NSValue .NSNumber实际上是NSValue的子类，NSValue可以包装任意值                    /**         +(NSValue *) valueWithBytes:(const void *) value objCType:(const char *) type;         传递的参数是你想要包装的数值的地址，通常，得到的是你想要存储的变量的地址（在c语言里适用操作符 & ），你也可以提供一个描述这个数据类型的字符串，通常用来说明struct中实体的类型和大小。你不用自己写代码         来生成这个字符串，@encode编译器指令可以接受数据类型的名称并为你生成合适的字符串         */          NSRect rect= NSMakeRect(1, 2, 30, 40);                    NSValue *value;          value=[NSValue valueWithBytes:&rect objCType:@encode(NSRect)];          NSMutableArray *mr=[NSMutableArray arrayWithCapacity:50];          [mr addObject:value];                     //getValue 提取数据          /**         -(void) getValue:(void *) value; 要传递的是存储这个数值的变量的地址         */                    /***        value=http://www.mamicode.com/[mr objectAtIndex:0];"00000 ===%@",r);        [value getValue:&r];        NSLog(@"111== %@",r);        */                    /**         +(NSValue *) valueWithPoint:(NSPoint) point;         +(NSValue *) valueWithSize:(NSSize) size;         +(NSValue *) valueWithRect:(NSRect) rect;                                       -(NSPoint) pointValue;         -(NSSize) sizeValue;         -(NSRect) rectValue;                   */                    //NSNull           /*         *+(NSNull *) null;          */          [mutableDic setObject:[NSNull null] forKey:@"fax"];          id fax;          fax=[mutableDic objectForKey:@"fax"];          if(fax==[NSNull null]){              NSLog(@"pppppppppppppppppp");          }                    [pool drain];          return 0;      }