Question

我试图让我的UIBarButtonItem从右侧滑入leftBarButtonItem位置。

滑动到错误的位置，然后在设置为leftBarButtonItem或根本不可见时跳转。这就是我现在正在尝试的事情..

func createLeftBarButton() {
    // Get the nav bar we'll be working with
    var toolbar = self.navigationItem
    // Initialise our button
    cancelButton = UIButton.buttonWithType(UIButtonType.Custom) as! UIButton
    cancelButton.setTitle("+", forState: UIControlState.Normal)
    cancelButton.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
    cancelButton.addTarget(self, action: "cancel:", forControlEvents: .TouchUpInside)
    cancelButton.titleLabel?.font = UIFont(name: "Courier", size: 34.0)

    // Create a placeholder to get the position and size of the leftBarButtonItem
    placeholderView = UIView(frame: cancelButton.bounds)
    placeholderView.backgroundColor = UIColor.clearColor()
    toolbar.leftBarButtonItem = UIBarButtonItem(customView: placeholderView)

    // Get the frame and position of the placeholderView
    var finalFrame: CGRect = self.view.convertRect(placeholderView.bounds, fromCoordinateSpace: placeholderView)

    // Set the frame for the button to the right of the final location.. this is probably wrong at the moment.
    cancelButton.frame = CGRectMake(-1 * cancelButton.bounds.size.width, finalFrame.origin.y, cancelButton.bounds.size.width, cancelButton.bounds.size.height)

    // Add the button to the view
    self.navigationController?.navigationBar.addSubview(cancelButton)
    // Animate it to the final position
    UIView.animateWithDuration(0.2, animations: {
        self.cancelButton.frame = finalFrame
        }, completion: { _ in
            // Finally set it to the leftBarButtonitem
            toolbar.leftBarButtonItem = UIBarButtonItem(customView: self.cancelButton)
    })


}

Answer 1

使用占位符视图/子视图的方法有点过于复杂。因此，您的代码根本不显示任何内容，因为您的cancelButton没有框架，然后您的占位符视图继承该空框架。但即便如此，你仍然会遇到问题，按钮会在下方滑动，然后再回弹。

认为这可以实现您的目标：

    func createLeftBarButton() {
    // Get the nav bar we'll be working with
    var toolbar = self.navigationItem
    // Initialise our button
    cancelButton = UIButton.buttonWithType(UIButtonType.Custom) as! UIButton
    cancelButton.setTitle("+", forState: UIControlState.Normal)
    cancelButton.setTitleColor(UIColor.blackColor(), forState: UIControlState.Normal)
    cancelButton.addTarget(self, action: "cancel:", forControlEvents: .TouchUpInside)
    cancelButton.titleLabel?.font = UIFont(name: "Courier", size: 34.0)
    cancelButton.frame = CGRectMake(0, 0, 20, 20)
    // Create a placeholder to get the position and size of the leftBarButtonItem
    toolbar.leftBarButtonItem = UIBarButtonItem(customView: cancelButton)

    var delta = self.cancelButton.frame.size.width
    cancelButton.frame = CGRectOffset(cancelButton.frame, -delta, 0.0)

    // Animate it to the final position
    UIView.animateWithDuration(0.2, animations: {
        self.cancelButton.frame = CGRectOffset(self.cancelButton.frame, delta, 0.0)
        }, completion: { _ in
    })
}

在NavigationItem中从右侧动画UIBarButtonItem

1 个答案: