NSArray的排序和乱序

 1   NSArray *array = @[@(3),@(4),@(1),@(2),@(5)];
 2      //升序
 3     NSArray *array1 = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
 4         return [obj1 compare:obj2];
 5     }];
 6     NSLog(@"%@",array1);
 7     
 8     //降序
 9     NSArray *array2 = [array sortedArrayUsingComparator:^NSComparisonResult(NSNumber *obj1,NSNumber *obj2) {
10         //相对于升序,compare参数调换一下
11         return [obj2 compare:obj1];
12     }];
13     NSLog(@"%@",array2);
14     
15     
16     //乱序
17     NSArray *array3 = [array sortedArrayUsingComparator:^NSComparisonResult(NSNumber *obj1,NSNumber *obj2) {
18         //0或者1的随机数
19         int i = arc4random_uniform(2);
20         if (i) {
21              return [obj1 compare:obj2];
22         }else{
23              return [obj2 compare:obj1];
24         }
25        
26     }];
27     NSLog(@"%@",array3);