Checking if viewWithTag exists before removingFromSuperview

Is it safe to use [[self.view viewWithTag:999] removeFromSuperview]; without checking if the view actually exists开发者_JAVA百科?

There is no error on simulator but will it cause no problem on a real device?

Is there any drawback of not using such condition?

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It is completely alright to call [[self.view viewWithTag:999] removeFromSuperview]; directly. If the view exists then [self.view viewWithTag:999] will return the view and it will be removed from its superview. If the view doesn't exists then [self.view viewWithTag:999] will return nil and passing any message to nil wont take any effect.

So, in your case, there is no need to check whether the view actually exists or not.

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Answer from the apple docs for UIView

If the receiver’s superview is not nil, the superview releases the receiver. If you plan to reuse a view, be sure to retain it before calling this method and release it again later as appropriate.

Never call this method from inside your view’s drawRect: method.

Nothing will happen when the view with the tag will return nil.