XCode 编译的时候，出线如下错误：
Undefined symbols for architecture armv7:
"_OBJC_CLASS_$_CALayer", referenced from:
objc-class-ref in EGORefreshTableHeaderView.o
"_CATransform3DIdentity", referenced from:
-[EGORefreshTableHeaderView setState:] in EGORefreshTableHeaderView.o
"_kCATransactionDisableActions", referenced from:
-[EGORefreshTableHeaderView setState:] in EGORefreshTableHeaderView.o
"_kCAGravityResizeAspect", referenced from:
-[EGORefreshTableHeaderView initWithFrame:] in EGORefreshTableHeaderView.o
"_CATransform3DMakeRotation", referenced from:
-[EGORefreshTableHeaderView setState:] in EGORefreshTableHeaderView.o
"_OBJC_CLASS_$_CATransaction", referenced from:
objc-class-ref in EGORefreshTableHeaderView.o
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)
其实 是你的 .frameWork没有添加进来。
添加动态库的方法或步骤如下：targets--->build phases----->link binary with libraries----->+选择要添加的库。
比如我少的就是QuartzCore.framework.