How do I weak link frameworks on Xcode 4?
Go to your project -> Targets -> Build Phases -> Link Binary with Libraries.
Then change the library you want to weak-link from "Required" to "Optional".
This doesn't work now. Please follow the link below:https://developer.apple.com/library/mac/#documentation/MacOSX/Conceptual/BPFrameworks/Concepts/WeakLinking.html
Select the target you want to modify and reveal its build phases.
Expand the Link Binary With Libraries build phase to view the frameworks currently linked by the target.
If the framework you want to weakly link to is listed in the Link Binary With Libraries build phase, select it, and choose Edit > Delete to remove it.
Now you can tell the linker to use weak linking for that framework.
Select the target, open its Info window, and click Build.
To the Other Linker Flags build setting, add the following command-line option specification, where FRAMEWORK_NAME is the name of the framework you want to weakly link to:-weak_framework FRAMEWORK_NAME
Build your product.