NSArray *array = @[@(3),@(4),@(1),@(2),@(5)];     //升序    NSArray *array1 = [array sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {        return [obj1 compare:obj2];    }];    NSLog(@"%@",array1);        //降序    NSArray *array2 = [array sortedArrayUsingComparator:^NSComparisonResult(NSNumber *obj1,NSNumber *obj2) {        //相对于升序,compare参数调换一下        return [obj2 compare:obj1];    }];    NSLog(@"%@",array2);            //乱序    NSArray *array3 = [array sortedArrayUsingComparator:^NSComparisonResult(NSNumber *obj1,NSNumber *obj2) {        //0或者1的随机数        int i = arc4random_uniform(2);        if (i) {             return [obj1 compare:obj2];        }else{             return [obj2 compare:obj1];        }           }];    NSLog(@"%@",array3);