Question

我试图在我的应用中设计一个视图，当UILabel内的文字与某个正则表达式不匹配时，该视图会显示错误UITextField。一切正常，除了我的UITextField包含无效条目，然后点击屏幕以关闭键盘。键盘解除后，UITextField移动到UITextView（红色文本）之上，我找不到原因。我在我的代码中设置了断点，但似乎在键盘解除后我的代码都没有执行。任何帮助表示赞赏。

//
//  ViewController.swift
//  KeyboardLabel
//

import UIKit

class ViewController: UIViewController {

    @IBOutlet var titleLabel:UILabel!
    @IBOutlet var errorLabel:UITextView!
    @IBOutlet var textBox:UITextField!
    @IBOutlet var createButton:UIButton!

    var deltaHeight:CGFloat!
    var beenMoved = true

    override func viewDidLoad() {
        super.viewDidLoad()

        // Register for notifications when the text in the text field is changed
        NSNotificationCenter.defaultCenter().addObserver(self, selector: "validateText", name: UITextFieldTextDidChangeNotification, object: textBox)

        // Add a gesture recognizer to dismiss the keyboard
        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "dismissKeyboard"))

        // Set the text of the labels
        titleLabel.text = "Container Number:"
        errorLabel.text = "Error, Invalid container number.\nRe-enter number."

        // Calculate the height to move the text field and button
        deltaHeight = errorLabel.frame.size.height + 8.0
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    func dismissKeyboard() {
        textBox.resignFirstResponder()
    }

    func validateText() {
        dispatch_async(dispatch_get_main_queue(), {
            // Regular expression for determining whether the text is valid
            let predicate  = NSPredicate(format: "SELF MATCHES %@", "[a-zA-Z0-9#]+")
            let empty = self.textBox.text!.isEmpty
            let valid = predicate.evaluateWithObject(self.textBox.text)

            // If the string is valid
            if valid || empty {
                // If the view has been moved down
                if(!self.beenMoved) {
                    // Hide the error label then move the text field and create button up
                    self.errorLabel.hidden = true
                    UIView.animateWithDuration(0.4, animations: {
                        self.textBox.frame.origin.y -= self.deltaHeight
                        self.createButton.frame.origin.y -= self.deltaHeight
                    })

                    // Flip the flag
                    self.beenMoved = true
                }
            }
                // If the string is invalid
            else {
                // If the view has been moved up
                if(self.beenMoved) {
                    // Show the error label then move the text field and create button down
                    UIView.animateWithDuration(0.4, animations: {
                        self.textBox.frame.origin.y += self.deltaHeight
                        self.createButton.frame.origin.y += self.deltaHeight
                        }, completion: {
                            (flag:Bool) in
                            self.errorLabel.hidden = false
                    })

                    // Flip the flag
                    self.beenMoved = false
                }
            }

            // If the text field is empty
            if empty {
                // Disable the create button
                self.createButton.enabled = false
            }
            else {
                // Enable the create button
                self.createButton.enabled = true
            }
        })
    }
}

Answer 1

行为实际上是这样的，如果你输入的东西与正则表达式不匹配，最初UITextField会移动到UITextView之上。这是因为您正在使用以下代码行移动UITextField和按钮：

/* on any screen smaller than 480px */ 

@media screen and (max-width: 480px) { 
  .cell-size {
    width: 100%;
  }
}

当键盘解除时，UITextField和UIButton返回其原始位置。我假设你对UI元素没有任何限制。

UITextField移动时出错

1 个答案: