objective-c - How to capture user input in real time in NSTextField?

Question

I can capture string when user click the button. and I also use the following method

- (BOOL)control:(NSControl *)control textShouldBeginEditing:(NSText *)fieldEditor

which declared in NSControlTextEditingDelegate Protocol. And when user begin editing, the button will be available.

My Question is: How to make the button disable when user delete all text (make the textField empty without clicking button)?

The above method seems can not do it...

Answer 1

如果你NSText是一个NSTextView你也可以使用NSTextDelegate Protocol和NSTextViewDelegate Protocol。

其中，NSTextDelegate协议声明了这个委托方法：

textDidChange:

通知委托文本对象已更改其字符或格式属性。

- (void)textDidChange:(NSNotification *)aNotification

讨论

aNotification 的名称是 NSTextDidChangeNotification。

NSTextDidChangeNotification此处记录了NSTextDidChangeNotification

Answer 2

查看使用文本字段发布的NSControlTextDidChangeNotification或controlTextDidChange:委托方法（from ）。NSControl当您收到回调时，您可以检查当前字段中的文本以决定做什么。

Answer 3

许多方法可以做同样的事情。此版本可让您轻松捕捉感兴趣的特定击键。

- (BOOL)textView:(NSTextView *)aTextView shouldChangeTextInRange:(NSRange)affectedCharRange replacementString:(NSString *)replacementString{
     NSLog(@"last character entered: %@",replacementString);
}

例如，如果您正在寻找返回键，那么您可以实现：

if ([replacementString characterAtIndex:0] == NSNewlineCharacter)
    NSLog(@"return pressed");