How do you use weak linking in an iPhone application? -

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how weak link frameworks when developing iphone?

once you've weak-linked framework, how use classes , methods may not present on os versions?

what want use weak linking for?

a common use use class defined in newer version of sdk. framework exists on older systems, class defined in framework doesn't.

if case use nsclassfromstring(). if returns nil, class doesn't exist, otherwise return class object can used.

this recommended way according apple in document:


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