问题
I've been getting some strange linking errors in XCode. I understand more or less what linking errors are, just not why they are showing up in my situation.
I have an app that started as iPhone only. When I adjusted it to be universal I got some odd linking errors. I then simply created a new universal project and imported the files, it built and executed without error. Now, working with the iPad interface, I've added some animations and am inheriting QuartzCore/QuartzCore.h but when I build, I get linking errors (shown below). What causes this sort of problem, how can I fix it, and how can I avoid it in the future?
"_OBJC_CLASS_$_CAMediaTimingFunction", referenced from:
objc-class-ref-to-CAMediaTimingFunction in mainViewController_iPad.o
"_OBJC_CLASS_$_CABasicAnimation", referenced from:
objc-class-ref-to-CABasicAnimation in mainViewController_iPad.o
"_kCAMediaTimingFunctionEaseIn", referenced from:
_kCAMediaTimingFunctionEaseIn$non_lazy_ptr in mainViewController_iPad.o
(maybe you meant: _kCAMediaTimingFunctionEaseIn$non_lazy_ptr)
"_OBJC_CLASS_$_CAKeyframeAnimation", referenced from:
objc-class-ref-to-CAKeyframeAnimation in mainViewController_iPad.o
"_OBJC_CLASS_$_CAAnimationGroup", referenced from:
objc-class-ref-to-CAAnimationGroup in mainViewController_iPad.o
"_CATransform3DIdentity", referenced from:
_CATransform3DIdentity$non_lazy_ptr in mainViewController_iPad.o
(maybe you meant: _CATransform3DIdentity$non_lazy_ptr)
ld: symbol(s) not found
collect2: ld returned 1 exit status
回答1:
You need to add QuartzCore.framework.
来源：https://stackoverflow.com/questions/4963980/what-causes-ios-linking-errors