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Concise syntax for the Pop animation framework.
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POP+MCAnimate License MIT

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Concise syntax for the Pop animation framework. For more on the motivation behind this experiment, read this blog post.


Add the following to your CocoaPods Podfile

pod 'POP+MCAnimate', '~> 2.0'

or clone as a git submodule,

or just copy files in the POP+MCAnimate folder into your project.

Using POP+MCAnimate

Breaking change: Methods and properties have been prefixed with pop_. See section on shorthand syntax below.

Replace this:

POPSpringAnimation *animation = [self.boxView pop_animationForKey:@"bounds"];
if (!animation) {
    animation = [POPSpringAnimation animationWithPropertyNamed:kPOPViewBounds];

animation.toValue = [NSValue valueWithCGRect:CGRectMake(0, 0, 200, 200)];
[self.boxView pop_addAnimation:animation forKey:@"bounds"];

With this:*

self.boxView.spring.bounds = CGRectMake(0, 0, 200, 200);

Spring Animation

You can configure velocity, springBounciness and springSpeed. = [pan velocityInView:self.boxView];
self.boxView.springBounciness = 20;
self.boxView.springSpeed = 20; = viewCenter;

Decay Animation

You can configure velocity and decayDeceleration. = [pan velocityInView:self.boxView];
self.boxView.decayDeceleration = 0.998;
[self.boxView.decay center];

Basic Animation

You can configure duration and use different timing functions by swapping out easeInEaseOut for easeIn, easeOut or linear.

self.boxView.duration = 1; = viewCenter;

Grouping and Completion Handlers

Block-based methods are provided on NSObject similar to UIKit block-based animation methods. The completion block waits for all animations in the animate block to complete before executing.

[NSObject animate:^{
  self.boxView.spring.alpha = 0.5;
  self.boxView.spring.bounds = CGRectMake(0, 0, 200, 200);
  self.boxView.spring.backgroundColor = [UIColor blueColor];
} completion:^(BOOL finished) {
  self.boxView.alpha = 1;
  self.boxView.spring.bounds = CGRectMake(0, 0, 100, 100);
  self.boxView.spring.backgroundColor = [UIColor redColor]; = viewCenter;

If you need to stop animations mid-way, use the stop proxy:

[self.boxView.stop bounds];

The finished flag in the completion handler will return NO if any of the animations in the group were stopped before completion.

Staggering Animations

Big thanks to @borndangerous and @bradjasper for their suggestion on beginTime. Great idea from @borndangerous on using sequences.

Set the beginTime property before any animations to stagger the animations by the said amount:

circle.beginTime = CACurrentMediaTime() + 0.1
circle.spring.alpha = 1;
circle.spring.scaleXY = CGPointMake(1, 1);

Once beginTime is set, it will persist until removed (by setting to 0), so all animations following that will be affected (which is probably what you want.)

If you work with NSArrays, it's even easier using the -sequenceWithInterval:animations:completion: method:

[circles sequenceWithInterval:0.1 animations:^(UIView *circle, NSInteger index){ = position;
    circle.spring.alpha = 1;
    circle.spring.scaleXY = CGPointMake(1, 1);
} completion:^(BOOL finished){

Custom Properties

You can make any property animatable by first declaring it:

[UILabel registerAnimatablePropertyWithName:@"textColor" readBlock:^(UILabel *label, CGFloat values[]) {
    POPUIColorGetRGBAComponents(label.textColor, values);
} writeBlock:^(UILabel *label, const CGFloat values[]) {
    label.textColor = POPUIColorRGBACreate(values);
} threshold:0.01];

You do this by providing a read block, write block and threshold to tell Pop how to get and set numerical values on your property and the smallest increment to change it by. Later, just animate as usual:

self.messageLabel.spring.textColor = [UIColor blackColor];


The above examples require the use of shorthand so you can drop the pop_ prefix from methods and properties. Just include the following in your pre-compiled header file after importing UIKit:

#import <POP+MCAnimate.h>


The list of supported properties are:

  • CALayer (and subclasses)

    • backgroundColor
    • bounds
    • opacity
    • position
    • zPosition
    • *pop_*positionX
    • *pop_*positionY
    • *pop_*rotation
    • *pop_*rotationX
    • *pop_*rotationY
    • *pop_*scaleX
    • *pop_*scaleY
    • *pop_*scaleXY
    • *pop_*translationX
    • *pop_*translationXY
    • *pop_*translationY
    • *pop_*translationZ
    • *pop_*size
  • CAShapeLayer

    • strokeColor
    • strokeStart
    • strokeEnd
  • NSLayoutConstraint

    • constant
  • UIView (and subclasses)

    • alpha
    • backgroundColor
    • bounds
    • center
    • frame
    • *pop_*scaleX
    • *pop_*scaleY
    • *pop_*scaleXY
  • UIScrollView (and subclasses)

    • contentOffset
    • contentSize


POP+MCAnimate is under the MIT license.

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