Quartz Core Import not required in Xcode 5?

问题

Just stumbled across this today. I am getting warnings in Xcode 4.6 if I try to access the CALayer without importing <QuartzCore/QuartzCore.h>. The same however works fine in Xcode 5.

回答1:

Yes, <QuartzCore/QuartzCore.h> is automatically included, but this seems to be more a side effect than intended, because it is included only indirectly:

• <UIKit/UIKit.h> includes <UIKit/UISlider.h>,
• in the iOS 7 SDK, <UIKit/UISlider.h> includes <QuartzCore/QuartzCore.h>, due to new instance variables in the UISlider class (of the CAShapeLayer type).

In addition, Xcode 5 has a new build setting "Link Frameworks Automatically", which is by default on (and requires the new "modules" feature), so that the QuartzCore framework is also added to the link libraries.

来源：https://stackoverflow.com/questions/20518085/quartz-core-import-not-required-in-xcode-5