如果文本字段为空,如何禁用按钮？

1> Steve..：

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既然你已经为你的班级做了一个UITextFieldDelegate广告这个功能

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    let text = (textField.text as NSString).stringByReplacingCharactersInRange(range, withString: string)

    if !text.isEmpty{
        continueButton.userInteractionEnabled = true 
    } else {
        continueButton.userInteractionEnabled = false 
    } 
    return true
}

还会更新您的viewDidLoad函数

override func viewDidLoad() {
    super.viewDidLoad()

    nounTextField.delegate = self
    if nounTextField.text.isEmpty{
        continueButton.userInteractionEnabled = false 
    }
}

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三个观察结果:我只是切换"启用",而不是修改`userInteractionEnabled`.其次,`UITextField`的`text`属性是可选的,所以当你把它转换为`NSString`时你必须打开它.第三,你可以将`if`-`else`子句简化为`continueButton.enabled =!text.isEmpty()`.