将NSUInteger分配给启用UIButton的属性在32位体系结构的设备中不起作用

Question

Just come cross a strange bug in devices with 32 bit architecture, below is the code:

- (void)textViewDidChange:(UITextView *)textView {
    self.button.enabled = textView.text.length;
}

So whenever I paste some text whose length is not 1 into the textView, (this is to imitate the behaviour of a third-party keyboard Sogou ), the button will not be enabled.

You can use this Demo to reproduce the bug.

I've read related posts, like Assigning NSUInteger to BOOL conceptual understanding , but this case is different.

Please tell me why it does not work here.

Answer 1

Don't think of it as a bug. Think of it as your code being wrong. This line is horrible:

self.button.enabled = textView.text.length;

You are trying to misuse a number as a BOOL. You are thus assuming that any non-zero number is the same as YES . That is a false assumption. Stop writing code like that. Write it like this:

self.button.enabled = (textView.text.length > 0);

That way, the BOOL really is a BOOL.