在POP源代码中如下代码片段：

struct _POPPropertyAnimationState : _POPAnimationState{  NSUInteger valueCount;  valueCount(nil)}

使用Xcode6.0.1打开项目会出现如下截图错误(Xcode5中不会出现)：

错误信息：Cannot initialize a member subobject of type ‘NSUInteger‘ (aka ‘unsigned long‘) with an rvalue of type ‘nullptr_t‘

将valueCount初始化为valueCount(0)后，问题解决了。

struct _POPPropertyAnimationState : _POPAnimationState{  NSUInteger valueCount;  valueCount(0)}

Xcode6中变量初始化的问题