Question

我正在使用“编程iOS 8”中的以下代码。我有一个带有约束的子视图，其中包含一个简单的文本字段。这个视图有超级视图约束的顶部和底部，我有出口。我也有子视图的出口。这里的目标是当键盘出现时，它会推动这个子视图。我在“let f = self.fr！.frame”一行中收到错误。主题1：EXC_BAD_INSTRUCTION。是否与需要拆开可选项有关？这可能是我的约束问题吗？任何帮助将非常感激。谢谢。

import UIKit

class ViewController: UIViewController {

@IBOutlet var topSpace: NSLayoutConstraint!
@IBOutlet var bottomSpace: NSLayoutConstraint!
@IBOutlet var slidingView: UIView!
var fr: UIView?

override func viewDidLoad() {
    NSNotificationCenter.defaultCenter().addObserver(
        self, selector: "keyboardShow:",
        name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(
        self, selector: "keyboardHide:",
        name: UIKeyboardWillHideNotification, object: nil)




    super.viewDidLoad()   

}


func textFieldDidBeginEditing(tf: UITextField) {
    self.fr = tf // keep track of the first responder
}

func textFieldShouldReturn(tf: UITextField) -> Bool {

    tf.resignFirstResponder()
    self.fr = nil
    return true

}

func keyboardShow(n:NSNotification) {
    let d = n.userInfo!
    var r = (d[UIKeyboardFrameEndUserInfoKey] as NSValue).CGRectValue()
    r = self.slidingView.convertRect(r, fromView:nil)
    let f = self.fr!.frame
    let y : CGFloat =
    f.maxY + r.size.height - self.slidingView.bounds.height + 5
    if r.origin.y < f.maxY {
        self.topSpace.constant = -y
        self.bottomSpace.constant = y
        self.view.layoutIfNeeded()
    }
}

func keyboardHide(n:NSNotification){
    self.topSpace.constant = 0
    self.bottomSpace.constant = 0
    self.view.layoutIfNeeded()
}



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


}

Answer 1

如果我没弄错，键盘会在您开始编辑之前显示，因此当您的键盘显示时，您的self.fr仍为零。检查它是否为零。它不应该对可选的展开做任何事情。它只在打开null时失败。

当键盘出现约束时，Swift-Move视图向上移动

1 个答案: