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IOS中NSSarry用法

2024-07-18 02:34:03   219人阅读

一、创建数组

// 创建一个空的数组  02.NSArray *array = [NSArray array];      03.// 创建有1个元素的数组  04.array = [NSArray arrayWithObject:@"123"];  05.// 创建有多个元素的数组  06.array = [NSArray arrayWithObjects:@"a", @"b", @"c", nil nil];  07.NSArray *array3 = [array arrayByAddingObjectsFromArray:[NSArray arrayWithObjects:@"4", @"5", nil nil]];  08.  09.NSArray *array4 = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];  10.NSRange range = NSMakeRange(1, 2);  11.NSArray *array5 = [array4 subarrayWithRange:range];

 

二、数组的基本用法

int count = [array count];//个数  02.// 判断是否包含了某个元素  03.if ([array containsObject:@"a"]) {  04.    NSLog(@"包含了字符串a");  05.}  06.NSString *last = [array lastObject];最后一个元素  07.NSString *str = [array objectAtIndex:1];根据索引获取数组中的元素  08.int index = [array indexOfObject:@"c"];获取指定元素的索引  09.// 让数组里面的所有对象都调用test方法，123为参数  10.NSArray *array = [NSArray arrayWithObjects:stu1, stu2, stu3, nil nil];  11.[array makeObjectsPerformSelector:@selector(test2:) withObject:@"123"];  12.NSArray *array = [NSArray arrayWithObjects:@"1", @"2", @"3", @"4", nil nil];  13.// 1-2-3-4  14.// 利用分隔符-拼接所有的数组元素  15.NSString *str = [array componentsJoinedByString:@"-"];  16.// 将一个数组写入文件（生成的是一个xml文件）  17.NSString *path = @"/Users/apple/Desktop/array.xml";  18.[array writeToFile:path atomically:YES];  19.path = @"/Users/apple/Desktop/array.txt";  20.// 从文件中读取数组内容（文件有严格的格式要求）  21.NSArray *array2 = [NSArray arrayWithContentsOfFile:path];

 三、遍历数组

#pragma mark 遍历数组1  02.void arrayFor1() {  03.    NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];  04.    int count = array.count;  05.    for (int i = 0; i<count; i++) {  06.        id obj = [array objectAtIndex:i];  07.    }  08.}  09.  10.#pragma mark 遍历数组2 快速遍历  11.void arrayFor2() {  12.    Student *stu1 = [Student student];  13.    NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];  14.    int i =0;  15.    for (id obj in array) {  16.        NSLog(@"%i-%@", i, obj);  17.        i++;  18.    }  19.}  20.  21.#pragma mark 遍历数组3  22.void arrayFor3() {  23.    Student *stu1 = [Student student];  24.    NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];  25.    [array enumerateObjectsUsingBlock:  26.     ^(id obj, NSUInteger idx, BOOLBOOL *stop) {  27.        NSLog(@"%i-%@", idx, obj);  28.         // 如果索引为1，就停止遍历  29.         if (idx == 1) {  30.             // 利用指针修改外面BOOL变量的值  31.             *stop = YES;  32.         }  33.    }];  34.}  35.  36.#pragma mark 遍历数组4  37.void arrayFor4() {  38.    Student *stu1 = [Student student];  39.    NSArray *array = [NSArray arrayWithObjects:stu1, @"1", @"2", @"3", nil nil];  40.    // 获取数组的迭代器  41.    // NSEnumerator *enumerator = [array objectEnumerator];  42.    // 反序迭代器（从尾部开始遍历元素）  43.    NSEnumerator *enumerator = [array reverseObjectEnumerator];  44.    // allObjects是取出没有被遍历过的对象  45.    NSArray *array2 = [enumerator allObjects];  46.    NSLog(@"array2:%@", array2);  47.    // 获取下一个需要遍历的元素  48.    id obj = nil;  49.    while (obj = [enumerator nextObject]) {  50.        NSLog(@"obj=%@", obj);  51.    }  52.}

 

 

四、数组排序

#pragma mark 数组排序1  02.void arraySort1() {  03.    NSArray *array = [NSArray arrayWithObjects:@"2", @"3", @"1", @"4", nil nil];  04.      05.    // 返回一个排好序的数组，原来数组的元素顺序不会改变  06.    // 指定元素的比较方法：compare:  07.    NSArray *array2 = [array sortedArrayUsingSelector:@selector(compare:)];  08.    NSLog(@"array2:%@", array2);  09.}  10.  11.#pragma mark 数组排序2  12.void arraySort2() {  13.    Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];  14.    Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];  15.    Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];  16.    Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];  17.    NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];  18.    // 指定排序的比较方法  19.    NSArray *array2 = [array sortedArrayUsingSelector:@selector(compareStudent:)];  20.    NSLog(@"array2:%@", array2);  21.}  22.- (NSComparisonResult)compareStudent:(Student *)stu {  23.    // 先按照姓排序  24.    NSComparisonResult result = [self.lastname compare:stu.lastname];  25.    // 如果有相同的姓，就比较名字  26.    if (result == NSOrderedSame) {  27.        result = [self.firstname compare:stu.firstname];  28.    }  29.    return result;  30.}  31.  32.#pragma mark 数组排序3  33.void arraySort3() {  34.    Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li"];  35.    Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang"];  36.    Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li"];  37.    Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao"];  38.    NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];  39.      40.    // 利用block进行排序  41.    NSArray *array2 = [array sortedArrayUsingComparator:  42.     ^NSComparisonResult(Student *obj1, Student *obj2) {  43.         // 先按照姓排序  44.         NSComparisonResult result = [obj1.lastname compare:obj2.lastname];  45.         // 如果有相同的姓，就比较名字  46.         if (result == NSOrderedSame) {  47.             result = [obj1.firstname compare:obj2.firstname];  48.         }  49.           50.         return result;  51.    }];  52.      53.    NSLog(@"array2:%@", array2);  54.}  55.  56.#pragma mark 数组排序4-高级排序  57.void arraySort4() {  58.    Student *stu1 = [Student studentWithFirstname:@"MingJie" lastname:@"Li" bookName:@"book1"];  59.    Student *stu2 = [Student studentWithFirstname:@"LongHu" lastname:@"Huang" bookName:@"book2"];  60.    Student *stu3 = [Student studentWithFirstname:@"LianJie" lastname:@"Li" bookName:@"book2"];  61.    Student *stu4 = [Student studentWithFirstname:@"Jian" lastname:@"Xiao" bookName:@"book1"];  62.    NSArray *array = [NSArray arrayWithObjects:stu1,stu2,stu3, stu4, nil nil];  63.      64.    // 1.先按照书名进行排序  65.    // 这里的key写的是@property的名称  66.    NSSortDescriptor *bookNameDesc = [NSSortDescriptor sortDescriptorWithKey:@"book.name" ascending:YES];  67.    // 2.再按照姓进行排序  68.    NSSortDescriptor *lastnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"lastname" ascending:YES];  69.    // 3.再按照名进行排序  70.    NSSortDescriptor *firstnameDesc = [NSSortDescriptor sortDescriptorWithKey:@"firstname" ascending:YES];  71.    // 按顺序添加排序描述器  72.    NSArray *descs = [NSArray arrayWithObjects:bookNameDesc, lastnameDesc, firstnameDesc, nil nil];  73.      74.    NSArray *array2 = [array sortedArrayUsingDescriptors:descs];  75.      76.    NSLog(@"array2:%@", array2);  77.}

 


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