在UITextField中有文本之前禁用UIButton

Question

如何在UITextField中有文本之前禁用UIButton.我的代码似乎不起作用.

    if ([nameTextField.text isEqualToString: @""]) {
            [myButton setEnabled:NO];
}

Answer 1

这是来自kingthong博客文章的代码,它对我有用:

- (void)viewDidLoad
{
    [super viewDidLoad];
    [self.saveButton setEnabled:NO];

    [[self myTextField] becomeFirstResponder];
    [myTextField addTarget:self 
                    action:@selector(textFieldDidChange)
          forControlEvents:UIControlEventEditingChanged];
}

- (void)textFieldDidChange
{
    if ([self.myTextField.text isEqualToString:@""]) {
        [self.saveButton setEnabled:NO];
    }
    else {
        [self.saveButton setEnabled:YES];
    }
}

Answer 2

保持按钮被禁用.实现UITextFieldDelegate并实现该方法:

- (void)textFieldDidBeginEditing:(UITextField *)textField;       

检查textField中文本的长度,如果大于0,则启用该按钮.