ios数组排序

- (void) sortMethod {

    NSComparator cmptr = ^(id obj1, id obj2) {

        if ([obj1 integerValue] > [obj2 integerValue]) {

            return (NSComparisonResult)NSOrderedDescending;

        }

        

        if ([obj1 integerValue] < [obj2 integerValue]) {

            return (NSComparisonResult)NSOrderedAscending;

        }

        

        return (NSComparisonResult) NSOrderedSame;

    };

    

    NSArray *sortArray = [[NSArray alloc] initWithObjects:@"1",@"3",@"4",@"7",@"8",@"2",@"6",@"5",@"13",@"15",@"12",@"20",@"28",@"",nil];



    //排序前

    NSLog(@"排序前:%@",[self formatOutPut:sortArray]);

    

    //第一种排序

    NSArray * array = [sortArray sortedArrayUsingComparator:cmptr];

    

    NSLog(@"排序后:%@",[self formatOutPut:array]);

    

    //第二种排序：利用sortedArrayUsingFunction 调用 对应方法customSort，这个方法中的obj1和obj2分别是指数组中的对象。



    array = [sortArray sortedArrayUsingFunction:customSort context:nil];

    NSLog(@"排序后:%@",[self formatOutPut:array]);



    

}



- (NSString *) formatOutPut:(NSArray *) array {

    NSMutableString * output = [[NSMutableString alloc] init];

    for (NSString * str in array) {

        [output appendFormat:@"%@ ",str];

    }



    return [output autorelease];

}

              



NSInteger customSort(id obj1, id obj2,void* context){

    if ([obj1 integerValue] > [obj2 integerValue]) {

        return (NSComparisonResult)NSOrderedDescending;

    }

    

    if ([obj1 integerValue] < [obj2 integerValue]) {

        return (NSComparisonResult)NSOrderedAscending;

    }

    

    return (NSComparisonResult)NSOrderedSame;

};