Question

您好我有一个NSMutableDictionary，其值为NSNumbers。我想创建一个函数，它返回NSMutableDictionary中最高的NSNumber值及其对应的键，而忽略一个键（“未指定”）？这是必须通过排序完成还是可以过滤一些方法？

Answer 1

如果有多个步骤，我会选择类似的东西：

NSMutableDictionary *slimDictionary = [originalDictionary mutableCopy];
[slimDictionary removeObjectForKey:@"Not Specified"];

NSNumber *maxValue = [[slimDictionary allValues] valueForKeyPath:@"@max.self"];

NSArray *allKeys = [slimDictionary allKeysForObject:maxValue];

// just return allKeys[0] if you know that there are definitely not multiple
// keys with the same value; otherwise do something deterministically to pick
// your most preferred key

Answer 2

您可以简单地枚举字典一次并跟踪最大字典值与相应的键一起：

NSDictionary *dict = @{@"a": @1, @"b": @2, @"Not Specified": @3};

__block NSString *highKey;
__block NSNumber *highVal;
[dict enumerateKeysAndObjectsUsingBlock:^(NSString *key, NSNumber *val, BOOL *stop) {
    if (highVal == nil || [val compare:highVal] == NSOrderedDescending) {
        if (![key isEqualToString:@"Not Specified"] ) {
            highKey = key;
            highVal = val;
        }
    }
}];

NSLog(@"key: %@, val: %@", highKey, highVal);
// Output: key: b, val: 2

在NSMutableDictionary中返回具有最高值的键

2 个答案: