Swift:成为 UITextField 上的第一响应者不工作? [英] Swift: Become First Responder on UITextField Not Working?

问题描述

我在 Storyboard 上创建了一个带有一个 UITextField 的自定义 UIViewController.在 viewDidLoad 上，我将 UITextFIeld 设置为 becomeFirstResponder，什么也没发生(没有键盘弹出).

I've created a custom UIViewController with one UITextField on Storyboard. On viewDidLoad, I set the UITextFIeld to becomeFirstResponder, nothing happened (no keyboards popped up).

然后我尝试调用 resignFirstResponder()，但它返回 false.接下来，我试图通过使用@在不使用私有 API 的情况下获取当前的第一响应者.事实证明，没有一个子视图是第一响应者.

I then tried calling resignFirstResponder(), but it returned false. Next I tried to find who the first responder is through looping all the subviews using the code over @ Get the current first responder without using a private API. It turns out none of the sub views are the first responder.

故事板中的我的 ViewController

My ViewController in storyboard

我的代码

class BLTestViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet var tf: UITextField

    override func viewDidLoad() {
        super.viewDidLoad()

        tf.delegate = self
        tf.becomeFirstResponder()
        // Do any additional setup after loading the view.
    }
}

就这么简单……为什么键盘没有出现！！！我做的一件事是自动布局，但我不确定这是否会影响键盘弹出.

As simple as it gets...WHY ISN'T THE KEYBOARD COMING UP!!! One thing I do have on is auto layout, but I'm not sure if that affects the keyboard popping up.

推荐答案

Swift 4 对我有用
试试吧

Swift 4 it worked for me
try it

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    
    textView.becomeFirstResponder()
    
}

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