我如何知道一个对象是否有一个键值观察者附加 [英] How can i tell if an object has a key value observer attached

问题描述

如果你告诉一个目标c对象removeObservers：对于一个键路径和该键路径没有注册，它破解sads。 like -

if you tell an objective c object to removeObservers: for a key path and that key path has not been registered, it cracks the sads. like -

'无法删除键路径theKeyPath的观察者，因为它未注册为观察员。

'Cannot remove an observer for the key path "theKeyPath" from because it is not registered as an observer.'

有一种方法可以确定对象是否有注册的观察者，所以我可以这样做

is there a way to determine if an object has a registered observer, so i can do this

if (object has observer){
  remove observer
}
else{
  go on my merry way
}

推荐答案

在你的removeObserver调用中加入try catch

Put a try catch around your removeObserver call

@try{
   [someObject removeObserver:someObserver forKeyPath:somePath];
}@catch(id anException){
   //do nothing, obviously it wasn't attached because an exception was thrown
}

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