NSDictionary 键按值数字排序

Question

我将名称作为键并将分数作为值存储到 NSDictionary 中，以便保存在 NSUserDefaults 中。然后我想取回按分数排序的键，但我似乎无法按数字排序，只能按字符串排序。例如，分数列表 100、50、300、200、500 给了我 100、200、300、50、500。

可以这样做还是我需要以不同的方式处理这个问题？

NSString *defaultNames[] = {@"Matt", @"Terry",@"Jessica",@"Sean",nil};
NSNumber *defaultScores[] = {@"600", @"500",@"100",@"50", nil};

NSDictionary *newScoreDict =  [NSDictionary dictionaryWithObjects:(id *)defaultScores forKeys:(id *)defaultNames count:7];

NSArray *currScores = [scoreDict keysSortedByValueUsingSelector:@selector(compare:)];

Answer 1

如何使用keysSortedByValueUsingSelector (NSDictionary)

似乎是您所需要的，根据XCode中的文档

Answer 2

NSString *defaultNames[] = {@"Matt", @"Terry",@"Jessica",@"Sean",nil};
NSNumber *defaultScores[] = {@"600", @"500",@"100",@"50", nil};
NSDictionary *newScoreDict =  [NSDictionary dictionaryWithObjects:(id *)defaultScores forKeys:(id *)defaultNames count:7];
NSArray *currScores = [scoreDict keysSortedByValueUsingSelector:@selector(localizedStandardCompare:)];

Answer 3

@implementation NSString (numericComparison)

- (NSComparisonResult) floatCompare:(NSString *) other
{
    float myValue = [self floatValue];
    float otherValue = [other floatValue];
    if (myValue == otherValue) return NSOrderedSame;
    return (myValue < otherValue ? NSOrderedAscending : NSOrderedDescending);
}

- (NSComparisonResult) intCompare:(NSString *) other
{
    int myValue = [self intValue];
    int otherValue = [other intValue];
    if (myValue == otherValue) return NSOrderedSame;
    return (myValue < otherValue ? NSOrderedAscending : NSOrderedDescending);
}

@end

NSString *defaultNames[] = {@"Matt", @"Terry",@"Jessica",@"Sean",nil};
// NSNumber *defaultScores[] = {@"600", @"500",@"100",@"50", nil};

NSNumber *defaultScores[] = {                                                                   
            [NSNumber  numberWithInt:600],
            [NSNumber  numberWithInt:500],
            [NSNumber  numberWithInt:100],
            [NSNumber  numberWithInt:50],
            nil 
    };

NSDictionary *newScoreDict =  [NSDictionary dictionaryWithObjects:(id *)defaultScores forKeys:(id *)defaultNames count:4];

NSArray *currScores = [newScoreDict keysSortedByValueUsingSelector:@selector(intCompare:NotSureWhatGoesHere:)];

我仍然对前一行感到困惑？

我是否只使用

//
NSArray *currScores = [newScoreDict keysSortedByValueUsingSelector:@selector(intCompare:other:)];
//

数字数组是否可以，还是有更简单的方法？

非常感谢...

Answer 4

-compare：是字符串比较。传递不同的方法进行比较，例如：

@implementation NSString (numericComparison)

- (NSComparisonResult) compareNumerically:(NSString *) other
{
float myValue = [self floatValue];
float otherValue = [other floatValue];
if (myValue == otherValue) return NSOrderedSame;
return (myValue < otherValue ? NSOrderedAscending : NSOrderedDescending);
}

@end

在您的具体情况下，您可以使用 -intValue 代替。

Answer 5

不确定这是否有帮助，但您也可以将 NSArray 保存在 plist 中；与 NSDictionary（它以基本上随机的顺序返回键）不同，您可以在放入键时将它们取回。

Answer 6

我认为这个问题最简单的方法是使用比较器..

NSString *defaultNames[] = {@"Matt", @"Terry",@"Jessica",@"Sean",nil};
NSNumber *defaultScores[] = {@(600), @(500),@(400),@(50), nil};
NSDictionary *newScoreDict =  [NSDictionary dictionaryWithObjects:defaultNames       forKeys:defaultScores count:4];
NSArray *currScores = [newScoreDict keysSortedByValueUsingComparator:^NSComparisonResult(id obj1, id obj2) {
    if ([obj1 integerValue] > [obj2 integerValue]) {
        return NSOrderedAscending;
    }else{
        return NSOrderedDescending;
    }}];

for (NSString *string in currScores) {
    NSLog(@"%@",string);
}

试试这个..
我注意到我无法使用 NSNumber 对象达到值，因此如果您想达到对象值，那么我可以通过将 NSNumber 分数更改为 NSString 并在订购时将它们转换为数字来解决。您可以像下面一样使用..

NSString *defaultNames[] = {@"Matt", @"Terry",@"Jessica",@"Sean",nil};
NSString *defaultScores[] = {@"600", @"500",@"400",@"50", nil};
NSMutableDictionary *newScoreDict =  [NSMutableDictionary   dictionaryWithObjects:defaultScores  forKeys:defaultNames count:4];

NSArray *currScores = [newScoreDict keysSortedByValueUsingComparator:^NSComparisonResult(id obj1, id obj2) {
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
NSNumber *number1 = [formatter numberFromString:obj1];
NSNumber *number2 = [formatter numberFromString:obj2];
    if (number1.intValue > number2.intValue) {
        return NSOrderedDescending;
    }else{
        return NSOrderedAscending;
    }}];

for (NSString *name in currScores) {
    NSLog(@"key %@ value %@",name,[newScoreDict valueForKey:name]);
}

希望它有帮助..