【iOS开发】Xcode 8.0 cannot create __weak reference in file using manual reference counting

问题描述：

__weak 这个属性修饰符不能再MRC文件中被引用。

解决方案：

Set Build Settings -> Apple LLVM 8.0 - Language - Objective C -> Weak References in Manual Retain Release to YES.

参考stackoverflow：

http://stackoverflow.com/questions/36147625/xcode-7-3-cannot-create-weak-reference-in-file-using-manual-reference-counting