从右向左移动按钮动画iOS-Swift

Question

I am creating an application with some buttons in a view controller. I want to add one animation like all the buttons are move from right to left. But all my buttons are moving from left to right. Here is my code.

 override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)
        b1_center_alignment.constant -= self.view.bounds.width;
        b2_center_alignment.constant -= self.view.bounds.width;
        b3_center_alignment.constant -= self.view.bounds.width;
        b4_center_alignment.constant -= self.view.bounds.width;
        b5_center_alignment.constant -= self.view.bounds.width;
}

override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated);
        UIView.animateWithDuration(0.5, delay: 0.0, options: UIViewAnimationOptions.CurveEaseOut, animations: {
            self.b5_center_alignment.constant += self.view.bounds.width
            self.view.layoutIfNeeded()
            }, completion: nil)

        UIView.animateWithDuration(0.5, delay: 0.3, options: UIViewAnimationOptions.CurveEaseOut, animations: {
            self.b4_center_alignment.constant += self.view.bounds.width
            self.view.layoutIfNeeded()
            }, completion: nil)


        UIView.animateWithDuration(0.5, delay: 0.6, options: UIViewAnimationOptions.CurveEaseOut, animations: {
            self.b3_center_alignment.constant += self.view.bounds.width
            self.view.layoutIfNeeded()
            }, completion: nil)
        UIView.animateWithDuration(0.5, delay: 0.9, options: UIViewAnimationOptions.CurveEaseOut, animations: {
            self.b2_center_alignment.constant += self.view.bounds.width
            self.view.layoutIfNeeded()
            }, completion: nil)

        UIView.animateWithDuration(0.5, delay: 1.2, options: UIViewAnimationOptions.CurveEaseOut, animations: {
            self.b1_center_alignment.constant += self.view.bounds.width
            self.view.layoutIfNeeded()
            }, completion: nil);

    }

I am very new to ios development. Please someone help me to solve this issue. Here b1_center_alignment, b2_center_alignment are center horizontal constraints from storyboard .

Answer 1

When you do

b1_center_alignment.constant -= self.view.bounds.width;

You're hiding the button on the left side of the screen, and then with

self.b5_center_alignment.constant += self.view.bounds.width

you move it back to it's original position

You need to invert the signals

b1_center_alignment.constant += self.view.bounds.width;

and self.b5_center_alignment.constant -= self.view.bounds.width