检查UIAppearance的可用性(Checking for availability of UIAppearance)

检查UIAppearance的可用性(Checking for availability of UIAppearance)

我正在尝试使用以下命令来检查UIAppearance类的可用性：

NSClassFromString(@"UIAppearance")

然而这从iOS4和iOS5返回零 - 任何人都有关于如何解决这个问题的提示？

I'm trying to check for the availability of the UIAppearance class using:

NSClassFromString(@"UIAppearance")

However this returns nil from both iOS4 and iOS5 - anyone got any tips on how to work around this?

最满意答案

UIAppearance不是一个类，它是一个协议。 所以为了检查它是否存在，你可以使用：

NSProtocolFromString(@"UIAppearance");

它在<iOS5上返回null，但是在iOS5上返回一个对象。

UIAppearance is not a class, it is a protocol. So in order to check wether it exists or not, you would use:

NSProtocolFromString(@"UIAppearance");

It returns null on < iOS5, but an object on iOS5.