如何以编程方式在iOS中获得较高的导航栏

Question

keyboardwillshown当键盘隐藏时，我必须将视图向上移动到正常位置

实际上，我在viewdidload方法上使用了以下代码：

override func viewDidLoad() { 

    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name: UIKeyboardWillShowNotification, object: nil)
    NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name: UIKeyboardWillHideNotification, object: nil) 

}

这是我用来上下移动的方法

func keyboardWillShow(notification:NSNotification){ 

    print("keyboardwillshow")
    let keyboardSize = (notification.userInfo?[UIKeyboardFrameEndUserInfoKey] as? NSValue)?.CGRectValue()

    self.view.frame = CGRectMake(0.0, -keyboardSize!.size.height + (self.navigationController?.navigationBar.frame.size.height)! + 20 , self.view.frame.size.width, self.view.frame.size.height )  

}

func keyboardWillHide(notification:NSNotification){

    self.view.frame = CGRectMake(0.0,(self.navigationController?.navigationBar.frame.size.height)!, self.view.frame.size.width, self.view.frame.size.height)
//  self.view.frame.origin.y += 350

}

当我运行该程序时，它将显示一个运行时错误，

意外发现展开时发现零

请帮我解决这个问题。

Answer 1

使用iPhone-X，顶部栏（导航栏+状态栏）的高度被更改（增加）。

如果您想要顶部栏（导航栏+状态栏）的确切高度，请尝试以下操作：

目标C

CGFloat topbarHeight = ([UIApplication sharedApplication].statusBarFrame.size.height +
       (self.navigationController.navigationBar.frame.size.height ?: 0.0));

斯威夫特4

let topBarHeight = UIApplication.shared.statusBarFrame.size.height +
        (self.navigationController?.navigationBar.frame.height ?? 0.0)

为方便起见，请尝试使用此UIViewController扩展

extension UIViewController {

    /**
     *  Height of status bar + navigation bar (if navigation bar exist)
     */

    var topbarHeight: CGFloat {
        return UIApplication.shared.statusBarFrame.size.height +
            (self.navigationController?.navigationBar.frame.height ?? 0.0)
    }
}

迅捷3

let topBarHeight = UIApplication.sharedApplication().statusBarFrame.size.height +
(self.navigationController?.navigationBar.frame.height ?? 0.0)

Answer 2

let navigationBarHeight = self.navigationController?.navigationBar.frame.height ?? 0