@interface _UIViewBackingObserver : NSObject @property (copy, nonatomic) id /* block */ observerBlock; + (id)sharedObserver; - (void)observeValueForKeyPath:(id)a0 ofObject:(id)a1 change:(id)a2 context:(void *)a3; - (void).cxx_destruct; - (void)observe:(id)a0 forKeyPath:(id)a1 once:(id /* block */)a2; @end