OC基础（2.3）SEL排序

main文件

#import <Foundation/Foundation.h>

void mySortUsingSelector(NSMutableArray * array,SEL selector)

{

    //取得数组中元素个数

    NSInteger count = [array count];

    // 冒泡排序,循环

    for (int i = 0; i<count-1; i++) {

        for (int j = 0; j<count-i-1; j++) {

            //取出数组中的  j 和 j+1对应的元素

            id obj1 = [array objectAtIndex:j];

            id obj2 = [array objectAtIndex:j+1];

            //让 obj1 执行选择器方法,参数为obj2,然后判断是否交换

            if ([obj1  performSelector:selector withObject:obj2]) {

                //如果满足条件,交换

                [array exchangeObjectAtIndex:j withObjectAtIndex:j+1];

            }

        }

    }

}

//给系统的字符串类,扩展两个比较方法

@interface NSString (Compare)

-(BOOL)compareForAsceding:(NSString *)obj;

-(BOOL)compareForDesceding:(NSString *)obj;

@end

//实现这两个方法

@implementation NSString (Compare)

-(BOOL)compareForAsceding:(NSString *)obj

{

    if ([self compare:obj] == NSOrderedDescending) {

        return YES;

    }

    return NO;

}

-(BOOL)compareForDesceding:(NSString *)obj

{

    if ([self compare:obj] == NSOrderedAscending) {

        return YES;

    }

    return NO;

}

@end

int main(int argc, const char * argv[]) {

    @autoreleasepool {

        // insert code here...

        NSLog(@"Hello, World!");

        

        NSMutableArray * mArray = [[NSMutableArray alloc]initWithObjects:@"1",@"2",@"3",@"7",@"4",@"9", nil];

        

        [mArray sortUsingSelector:@selector(compareForAsceding:)];

        

        NSLog(@"%@",mArray);

        

        mySortUsingSelector(mArray, @selector(compareForDesceding:));

        

        NSLog(@"%@",mArray);

    }

    return 0;

}