UITabBarItem Icon Animation

Question

Skype app for iPhone uses animated TabBar icons. For example, during the logging-in the rightmost tab icon shows circulating arrows. While calling the "Call" tab icon softly blinks which is obviously done through animation.

I wonder how is it possible to animate tab bar items' icons.

In my particular case when the user presses the 'Favorite' button it jumps onto the 'Favorites' tab bar item. I have already implemented the jumping animation, but I would like the corresponding tab bar icon to blink at the end of animation to bring the feeling of completeness to it.

Any suggestions about the direction I should look in?

Thanks in advance.

Answer 1

I am surprised how easy the solution was!

Add method to your Application Delegate class .m-file (or any other class that manages your UITabBar) containing the following routine:

1. Create an UIImageView that will be used for animation.
2. Add it to your TabBar view using the addSubview: method.
3. Frame it down to the size of UITabBarItem (use UITabBar frame size and the number of tab bar items to calculate the frame size).
4. Adjust the imageView's frame.origin.x value to place the Image right above the tab bat item you want to animate.
5. Add animation you want to the imageView (you can play with opacity, swap several images - anything you want).

Pretty easy, don't you think so?

You can call this method on UIApplicationDelegate instance anywhere you need to animate the tab bar item.

Also it is important to notice that you can tap THROUGH the imageView to select the tab bar item as if there was no image over the tab bar. Many interesting conclusions can be done here on what you can do if you know it...

Answer 2

I have found a better solution to this problem. Adding custom image view is not a better approach because in iOS 10.0 and later on changing the orientation the icon frame & text position changed. You just need to set the class of UITabBarController & put the following code.

override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {

    let index = self.tabBar.items?.index(of: item)
    let subView = tabBar.subviews[index!+1].subviews.first as! UIImageView
    self.performSpringAnimation(imgView: subView)
}

//func to perform spring animation on imageview
func performSpringAnimation(imgView: UIImageView) {

    UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {

        imgView.transform = CGAffineTransform.init(scaleX: 1.4, y: 1.4)

        //reducing the size
        UIView.animate(withDuration: 0.5, delay: 0.2, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
            imgView.transform = CGAffineTransform.init(scaleX: 1, y: 1)
        }) { (flag) in
        }
    }) { (flag) in

    }
}  

Answer 3

Keep in mind that the order of the subviews in the UITabBar may be unordered so accessing the correct item from it using an index may not work correctly as Naresh answer suggested. Have a look at this post UITabBar subviews change order

The solution I found is to first filter and sort the views and then access it using the correct index of the tabBarItem.

func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {

    let orderedTabBarItemViews: [UIView] = {
        let interactionViews = tabBar.subviews.filter({ $0 is UIControl })
        return interactionViews.sorted(by: { $0.frame.minX < $1.frame.minX })
    }()

    guard
        let index = tabBar.items?.firstIndex(of: item),
        let subview = orderedTabBarItemViews[index].subviews.first
    else {
        return
    }

    performSpringAnimation(for: subview)
}

func performSpringAnimation(for view: UIView) {
    UIView.animate(withDuration: 0.5, delay: 0, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
        view.transform = CGAffineTransform(scaleX: 1.25, y: 1.25)
        UIView.animate(withDuration: 0.5, delay: 0.2, usingSpringWithDamping: 0.5, initialSpringVelocity: 0.5, options: .curveEaseInOut, animations: {
            view.transform = CGAffineTransform(scaleX: 1, y: 1)
        }, completion: nil)
    }, completion: nil)
}

Answer 4

Actually there is much easier way: https://medium.com/@werry_paxman/bring-your-uitabbar-to-life-animating-uitabbaritem-images-with-swift-and-coregraphics-d3be75eb8d4d#.8o1raapyr

Answer 5

You can animate tabbar icons by getting its view, then do whatever animation as you like for the UIView. Below is a simple example with scale transform, cheer!

func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem){
        var tabBarView: [UIView] = []

        for i in tabBar.subviews {
            if i.isKind(of: NSClassFromString("UITabBarButton")! ) {
                tabBarView.append(i)
            }
        }

        if !tabBarView.isEmpty {
            UIView.animate(withDuration: 0.15, animations: {
                tabBarView[item.tag].transform = CGAffineTransform(scaleX: 1.2, y: 1.2)
            }, completion: { _ in
                UIView.animate(withDuration: 0.15) {
                    tabBarView[item.tag].transform = CGAffineTransform.identity
                }
            })
        }
    }

ps: please assign tag for each UITabBarItem in order

Answer 6

Index of UIImageView in subviews is not guaranteed as fist.

The index of UIImageView is not guaranteed as fist in related subviews.

So it is better to access it via class type, and also check for index out of bounds.

override func tabBar(_ tabBar: UITabBar, didSelect item: UITabBarItem) {
    guard let idx = tabBar.items?.firstIndex(of: item),
        tabBar.subviews.count > idx + 1,
        let imageView = tabBar.subviews[idx + 1].subviews.compactMap({ $0 as? UIImageView }).first else {
        return
    }
    
    imageView.layer.add(bounceAnimation, forKey: nil)
}

This is a sample basic bounce animation for that using CAKeyframeAnimation:

private var bounceAnimation: CAKeyframeAnimation = {
    let bounceAnimation = CAKeyframeAnimation(keyPath: "transform.scale")
    bounceAnimation.values = [1.0, 1.3, 0.9, 1.0]
    bounceAnimation.duration = TimeInterval(0.3)
    bounceAnimation.calculationMode = CAAnimationCalculationMode.cubic
    return bounceAnimation
}()

Answer 7

Simple way to animate tab bar item in objective c

In your tabbar controller class

    - (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
    {
        UIVisualEffectView *viv = tabBar.subviews[item.tag].subviews.firstObject;
        UIImageView *img = viv.contentView.subviews.firstObject;
       // If UIImageView not get use this code
       // UIImageView *img  = tabBar.subviews[item.tag].subviews.lastObject;


        [self shakeAnimation:img];
      //[self bounceAnimation:img];

    }



- (void)shakeAnimation:(UIImageView *)img
{
    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"position"];
    [animation setDuration:0.05];
    [animation setRepeatCount:2];
    [animation setAutoreverses:YES];
    [animation setFromValue:[NSValue valueWithCGPoint: CGPointMake([img center].x - 10.0f, [img center].y)]];
    [animation setToValue:[NSValue valueWithCGPoint: CGPointMake([img center].x + 10.0f, [img center].y)]];
    [[img layer] addAnimation:animation forKey:@"position"];
}


- (void)bounceAnimation:(UIImageView *)img
{
    img.transform = CGAffineTransformScale(CGAffineTransformIdentity, 0.001, 0.001);

    [UIView animateWithDuration:0.3/1.5 animations:^{
        img.transform = CGAffineTransformScale(CGAffineTransformIdentity, 1.1, 1.1);
    } completion:^(BOOL finished) {
        [UIView animateWithDuration:0.3/2 animations:^{
            img.transform = CGAffineTransformScale(CGAffineTransformIdentity, 0.9, 0.9);
        } completion:^(BOOL finished) {
            [UIView animateWithDuration:0.3/2 animations:^{
                img.transform = CGAffineTransformIdentity;
            }];
        }];
    }];
}

Answer 8

I haven't done that but I would just try to build a CAAnimation e.g. with a CABasicAnimation and add it to the UITabBarItem you want to be animated.

For details about how to set up a CABasicAnimation see the Core Animation Programming Guide: http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/CoreAnimation_guide/Articles/AnimatingLayers.html#//apple_ref/doc/uid/TP40006085-SW1