ios - 如何以编程方式在 iOS 中获取导航栏高度

Question

当 keyboardwillshown 时，我必须向上移动我的 View ，然后当键盘隐藏时，它回到正常位置

实际上我在 viewdidload 方法上使用了这段代码:

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

}

当我运行这个程序时，它会显示一个运行时错误

unexpected found a nil while unwrapping

请帮我解决这个问题。

Answer 1

对于 iPhone-X，顶部栏(导航栏 + 状态栏)的高度已更改(增加)。

如果你想要顶栏(导航栏+状态栏)的精确高度，试试这个:

objective-C

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

swift 4

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

为方便起见，试试这个 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)
    }
}

swift 3

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