ios - 检测何时停止在 UITextField 中输入

Question

我应该如何检测 UITextField 中的输入是否停止？我应该使用某种 UITextFieldTextDidEndEditingNotification 函数吗？我试图创建一个类似搜索的 instagram，它会在一秒钟不输入后显示结果。

Answer 1

我就是这样做的，它适用于 Swift 3

import UIKit

// don't forget to add UITextFieldDelegate
class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet var textField: UITextField!

    var searchTimer: Timer?

    override func viewDidLoad() {
        super.viewDidLoad()

        // declare textField as delegate
        self.textField.delegate = self

        // handle the editingChanged event by calling (textFieldDidEditingChanged(-:))
        self.textField.addTarget(self, action: #selector(textFieldDidEditingChanged(_:)), for: .editingChanged)
    }

    // reset the searchTimer whenever the textField is editingChanged
    func textFieldDidEditingChanged(_ textField: UITextField) {

        // if a timer is already active, prevent it from firing
        if searchTimer != nil {
            searchTimer?.invalidate()
            searchTimer = nil
        }

        // reschedule the search: in 1.0 second, call the searchForKeyword method on the new textfield content
        searchTimer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(searchForKeyword(_:)), userInfo: textField.text!, repeats: false)
    }

    func searchForKeyword(_ timer: Timer) {

        // retrieve the keyword from user info
        let keyword = timer.userInfo!

        print("Searching for keyword \(keyword)")
    }

}