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数组的排序及筛选
sortedArrayUsingComparator
NSArray *array = @[@"4",@"2",@"3",@"1",@"3"];NSLog(@"排序前: %@",array);NSComparator comparator = ^(id obj1, id obj2){ if([obj1 integerValue] > [obj2 integerValue]) { return NSOrderedDescending; } if([obj1 integerValue] < [obj2 integerValue]) { return NSOrderedAscending; } return NSOrderedSame; //return (arc4random() % 3) - 1; //随机排序};array = [array sortedArrayUsingComparator:comparator];NSLog(@"排序后: %@",array);
sortedArrayUsingFunction:customSort
- (void)viewDidLoad{ [super viewDidLoad]; NSArray *array = @[@"4",@"2",@"3",@"1",@"3"]; NSLog(@"排序前: %@",array); array = [array sortedArrayUsingFunction:customSort context:nil]; NSLog(@"排序后: %@",array);} NSInteger customSort(id obj1, id obj2, void* context){ if ([obj1 integerValue] > [obj2 integerValue]) { return NSOrderedDescending; } if ([obj1 integerValue] < [obj2 integerValue]) { return NSOrderedAscending; } return NSOrderedSame;}
sortUsingDescriptors
#import <Foundation/Foundation.h>@interface TopMenuItem : NSObject@property (strong, nonatomic) NSString *title;@property (assign, nonatomic) NSInteger order;@property (assign, nonatomic) BOOL selected;@end#import "TopMenuItem.h"@implementation TopMenuItem- (NSString *)description{ return [NSString stringWithFormat:@"title:%@, order:%d, selected:%d",self.title,self.order,self.selected];}@end- (void)viewDidLoad{ [super viewDidLoad]; NSMutableArray *channelArray = [NSMutableArray array]; TopMenuItem *item = [[TopMenuItem alloc] init]; item.title = @"要闻"; item.order = 1; item.selected = YES; [channelArray addObject:item]; item = [[TopMenuItem alloc] init]; item.title = @"半导体照明"; item.selected = YES; item.order = 3; [channelArray addObject:item]; item = [[TopMenuItem alloc] init]; item.title = @"电子工程"; item.selected = YES; item.order = 2; [channelArray addObject:item]; item = [[TopMenuItem alloc] init]; item.title = @"光通讯"; item.selected = NO; item.order = 3; [channelArray addObject:item]; NSLog(@"排序前"); for (TopMenuItem *item in channelArray) { NSLog(@"%@",item); } NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"order" ascending:YES]; NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"selected" ascending:YES]; [channelArray sortUsingDescriptors:[NSArray arrayWithObjects:sortDescriptor1, sortDescriptor2, nil]]; NSLog(@"排序后"); for (TopMenuItem *item in channelArray) { NSLog(@"%@",item); }}
makeObjectsPerformSelector
这个方法可以让数组内的所有元素都执行同一个对象方法，在特定场合可以替代for循环使用。
还是沿用上面例子里的TopMenuItem类，新加入一个方法：
- (void)testFun:(NSString *)str{ NSLog(@"testFun,param is:%@,title is %@",str,self.title);}
然后就可以这样调用：
[channelArray makeObjectsPerformSelector:@selector(testFun:) withObject:@"测试"];
NSPredicate
Cocoa框架中的NSPredicate主要用于查询并过滤元素，比较类似于Sql语句中的where，使用方法如下：
NSArray *array = @[@"A",@"AB",@"ABC",@"D",@"DF"];NSLog(@"排序前: %@",array);NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF Contains ‘A‘"];NSArray *newArray = [array filteredArrayUsingPredicate:predicate];NSLog(@"排序后: %@",newArray);
如果是NSMutableArray，则可以直接调用filterUsingPredicate来过滤原数组。
比较运算符
> >= < <= == !=(或<>)
NSMutableArray *array = [NSMutableArray arrayWithArray:@[[NSNumber numberWithInt:1], [NSNumber numberWithInt:4], [NSNumber numberWithInt:23], [NSNumber numberWithInt:999], [NSNumber numberWithInt:83],]];NSLog(@"原数组: %@",array);NSString *filterString = @"SELF>50"; //get 83,999filterString = @"SELF==23"; //get 23filterString = @"SELF<=23"; //get 1,4,23 NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString]; [array filterUsingPredicate:predicate];NSLog(@"过滤后: %@",array);
范围运算符
IN BETWEEN
NSMutableArray *array = [NSMutableArray arrayWithArray:@[[NSNumber numberWithInt:1], [NSNumber numberWithInt:4], [NSNumber numberWithInt:23], [NSNumber numberWithInt:999], [NSNumber numberWithInt:83],]];NSLog(@"原数组: %@",array);NSString *filterString = @"SELF BETWEEN {4,50}"; //get 4,23filterString = @"SELF IN {23,999}"; //get 23,999NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];[array filterUsingPredicate:predicate];NSLog(@"过滤后: %@",array);
字符串比较
LIKE BEGINWITH CONTAINS ENDSWITH MATCHES
NSArray *array = @[@"park",@"army",@"phone",@"warrior",@"stone",@"ear",@"apple",@"application",@"wear"];NSString *filterString = @"SELF LIKE[cd] ‘*ar‘"; //get "ear","wear"filterString = @"SELF LIKE[cd] ‘?ar‘"; //get "ear"filterString = @"SELF LIKE[cd] ‘?ar?‘"; //get "park"filterString = @"SELF LIKE[cd] ‘?ar*‘ && SELF ENDSWITH[cd] ‘r‘"; //get "warrior","ear"filterString = @"SELF BEGINSWITH[cd] ‘e‘ || SELF BEGINSWITH[cd] ‘s‘"; //get "stone","ear"(匹配以"e"或"s"开头的单词)filterString = @"SELF BEGINSWITH[cd] ‘app‘"; //get "apple","application"filterString = @"SELF ENDSWITH[cd] ‘one‘"; //get "stone","phone"filterString = @"SELF MATCHES[cd] ‘^w.+r$‘"; //get "warrior","wear"(正则匹配以"w"开头，"r"结尾的单词)NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];NSLog(@"过滤结果: %@",[array filteredArrayUsingPredicate:predicate]);
上面的例子都是直接利用SELF比较，如果数组存储的是对象，要以对象的属性值作为筛选目标可以这样：
NSMutableArray *channelArray = [NSMutableArray array];TopMenuItem *item = [[TopMenuItem alloc] init];item.title = @"要闻";item.order = 1;item.selected = YES;[channelArray addObject:item];item = [[TopMenuItem alloc] init];item.title = @"半导体照明";item.selected = NO;item.order = 5;[channelArray addObject:item];item = [[TopMenuItem alloc] init];item.title = @"电子工程";item.selected = YES;item.order = 2;[channelArray addObject:item];item = [[TopMenuItem alloc] init];item.title = @"光通讯";item.selected = NO;item.order = 3;[channelArray addObject:item];item = [[TopMenuItem alloc] init];item.title = @"太阳能光伏";item.selected = YES;item.order = 4;[channelArray addObject:item];NSString *filterString = @"title CONTAINS[cd] ‘光‘";filterString = @"selected==1";filterString = @"order BETWEEN {3,5}";NSPredicate *predicate = [NSPredicate predicateWithFormat:filterString];NSArray *filteredArray = [channelArray filteredArrayUsingPredicate:predicate];for (TopMenuItem *item in filteredArray){ NSLog(@"%@",item);}
数组的排序及筛选
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