objective-c - NSUSerDefaults 与 NSMutableArray 按 desc 顺序排序

Question

我很困惑为什么降序排序不适用于以下代码。我想通过前 5 名分数和其他逻辑来限制。分数将如下所示:22/30、12/18、34/38、23/32 等。我添加/删除了 SortDescriptor 以按降序排序，它似乎适用于前 3 个项目，但随后无法正确排序。有人可以帮忙吗？

- (NSMutableArray*) method1:(NSString *) mode byScore: (NSString *) score
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSMutableArray *array = [[defaults objectForKey:mode]mutableCopy];

    if (!array)
    {
        array = [[NSMutableArray alloc] init];
    }
    NSLog(@"The content of array is%@", array);

    if ([array count] < 5)
    {
      if (![array containsObject:score])
      {
          [array addObject:score];
          // Need to sort here. But not too sure this is the right place
          NSLog(@"The content of the sorted array upto 5 is%@", array); 
      }
    }
    else
    {
       if (![array containsObject:score])
       {
           if ([array lastObject] < score)
           {
               [array addObject:score];
               // Need to sort here before I remove the last object                   
               [array removeLastObject];
               NSLog(@"The content of the sorted array else is%@",array);
           }
       }
    }
    [defaults setObject:array forKey:mode];
    [defaults synchronize];
    // I want the array in NSUserDefaults to be sorted in desc order
    // don't know what to return here ==> the array object or the defaults object cast    to NSMutableArray?
}

Answer 1

辅助函数

static NSComparisonResult CompareFloats( float a, float b )
{
    if ( a < b ) { return NSOrderedAscending ; }
    else if ( a > b ) { return NSOrderedDescending ; }
    return NSOrderedSame ;
}

NSString 上的类别

@implementation NSString (Stuff)

-(float)floatValueForFraction
{
    NSArray * components = [ self componentsSeparatedByString:@"/" ] ;
    return [ components[0] floatValue ] / [ components[1] floatValue ] ;
}

@end

你的方法:

- (void)addScore:(NSString*)score forMode:(NSString*)mode
{
    NSUserDefaults * defaults = [ NSUserDefaults standardUserDefaults ] ;
    NSArray * scores = [ defaults objectForKey:mode ] ;

    scores = scores ? [ scores arrayByAddingObject:score ] : @[ score ] ;
    scores = [ scores sortedArrayUsingComparator:^(NSString * a, NSString * b){
        return CompareFloats( [ a floatValueForFraction ], [ b floatValueForFraction ] ) ;
    }]

    if ( scores.count > 5 ) { scores = [ scores subarrayWithRange:(NSRange){ .length = 5 } ] ; }

    [ default setObject:scores forKey:mode ] ;
}

如果您想在调用此方法后更新高分，只需使用 [ [ NSUserDefaults standardUserDefaults ] objectForKey:<mode> ] .最好让你的方法只做一件事。