Swift：成为 UITextField 上的第一响应者不工作？

Question

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).

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.

My ViewController in storyboard

My Code

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.
    }
}

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.

Answer 1

Swift 4 it worked for me
try it

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

Answer 2

I just tested it with a textfield by calling self.tf.becomeFirstResponder() indside viewDidLoad() function and its working absolutely fine. You'll need to toggle your keyboard by pressing command + K as nflacco just pointed out and disable the hardware keyboard in the simulator as:

1. iOS Simulator -> Hardware -> Keyboard
2. Uncheck "Connect Hardware Keyboard"

Answer 3

I think

class BLTestViewController: UIViewController, UITextFieldDelegate {

@IBOutlet var tf: UITextField

    override func viewDidLoad() {
        super.viewDidLoad()

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

    func focustf(){
    self.tf.becomeFirstResponder()
    }
}

Answer 4

Swift 4 and iOS 11

In my case, no mater what I tried, I was not able to set first responder until I tried this.

func tableView(_ tableView: UITableView, willDisplay cell: UITableViewCell, forRowAt indexPath: IndexPath) {
    if cell.isKind(of: YOURTABLEVIEWCELL.self) {
        if let yourCell = cell as? YOURTABLEVIEWCELL{
            yourCell.yourUiTextField.becomeFirstResponder()
        }
    }
}

Hope this helps someone stuck with the same problem.

Answer 5

按 command+shift+k 打开键盘。

Answer 6

try with this

 DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
                    textField.becomeFirstResponder()
                }

sometimes the wrong is the time in render the view