xcode 从 CFDictionary 中获取值
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Getting values from a CFDictionary
提问by Eric Brotto
I'm trying to access the values from a CFDictionary. I've started by implementing code suggested in this question:
我正在尝试从 CFDictionary 访问值。我已经开始实施这个问题中建议的代码：
CFTypeRef r = IOPSCopyPowerSourcesInfo();
CFArrayRef array = IOPSCopyPowerSourcesList(r);
CFDictionaryRef powerDic = IOPSGetPowerSourceDescription(array, r);
I have looked at the documentation plus other posts, but it's a bit beyond me how to work it.
我已经查看了文档和其他帖子，但它有点超出我的工作范围。
What I really need is some example code that takes the code I already have and uses it to print a string of, for example, "Current Capacity".
我真正需要的是一些示例代码，它采用我已有的代码并使用它来打印一个字符串，例如“当前容量”。
回答by Dave DeLong
CFDictionaryRefis "toll free bridged" with NSDictionary. This means you can cast one to the other interchangeably. In other words:
CFDictionaryRef与NSDictionary. 这意味着您可以交替地将一个转换为另一个。换句话说：
...
NSDictionary * powerDic = (NSDictionary *)IOPSGetPowerSourceDescription(array, r);
NSString * aValue = [powerDic objectForKey:@"aKey"];
If (for some reason) you need to stay at the CoreFoundation level (which isn't unheard-of), you'd use something like CFDictionaryGetValue().
如果（出于某种原因）您需要保持在 CoreFoundation 级别（这并非闻所未闻），您可以使用类似CFDictionaryGetValue().
