Make any UIView (e.g., UICollectionViewCell) wiggle like iOS home screen apps before being deleted

UIView+Wiggle.h

//
//  UIView+Wiggle.h
//

@interface UIView (Wiggle)
  
- (void)wiggle;
- (void)endWiggling;

- (BOOL)isWiggling;

@end

UIView+Wiggle.m

//
//  UIView+Wiggle.m
//

static NSString * const kWiggleRotation = @"wiggleRotation";
static NSString * const kWigglePosition = @"wigglePosition";

// default values
static CGFloat const kVWiggleVariance = 0.16;

static CGFloat const kMinAngle = 1.00;
static CGFloat const kRotationDuration = 0.19;

static CGFloat const kPositionDuration = 0.55;
static CGFloat const kPositionAnimationValues[] = {
    -0.20f,
    0.60f,
    -0.40f,
    0.46f,
    -0.32f
}; // size must be equal to kPositionAnimationKeyTimes
static CGFloat const kPositionAnimationKeyTimes[] = {
    0.f/6.f, // must be 0
    1.f/6.f,
    3.f/6.f,
    5.f/6.f,
    6.f/6.f // must be 1
}; // size must be equal to kPositionAnimationValues

#import "UIView+Wiggle.m"

@implementation UIView (Wiggle)

- (void)wiggle {
    [self wiggleWithVariance:kVWiggleVariance
                    minAngle:kMinAngle
            rotationDuration:kRotationDuration
            positionDuration:kPositionDuration];
}

- (void)wiggleWithVariance:(CGFloat)variance
                  minAngle:(CGFloat)minAngle
          rotationDuration:(CGFloat)rotationDuration
          positionDuration:(CGFloat)positionDuration {
    
    if (self.isWiggling) {
        [self endWiggling];
    }
    
    // ROTATION
    CABasicAnimation *rotateAnimation = CABasicAnimation.animation;
    rotateAnimation.keyPath = @"transform.rotation";
    
    CGFloat random = arc4random_uniform(100) / 100.f;
    CGFloat appliedVariance = variance * random;
    
    rotateAnimation.duration = rotationDuration * (1 - variance) + (rotationDuration * appliedVariance);
    rotateAnimation.repeatCount = CGFLOAT_MAX;
    rotateAnimation.autoreverses = YES;
    CGFloat extraAngle = minAngle * random;
    CGFloat fromAngle = (minAngle - extraAngle) * M_PI / 180;
    CGFloat toAngle = (minAngle + extraAngle) * M_PI / 180;
    
    rotateAnimation.fromValue = @(-fromAngle);
    rotateAnimation.toValue = @(toAngle);
    
    [self.layer addAnimation:rotateAnimation forKey:kWiggleRotation];
    
    // POSITION
    CAKeyframeAnimation *positionAnimation = [CAKeyframeAnimation animation];
    positionAnimation.keyPath = @"position.x";
    positionAnimation.duration = positionDuration * (1 - variance) + (positionDuration * appliedVariance);
    positionAnimation.repeatCount = CGFLOAT_MAX;
    positionAnimation.autoreverses = YES;
    positionAnimation.values = processedAnimationValues(appliedVariance);
    positionAnimation.keyTimes = processedAnimationKeyTimes();
    positionAnimation.additive = YES;
    [self.layer addAnimation:positionAnimation forKey:kWigglePosition];
}

static NSArray* processedAnimationValues (CGFloat appliedVariance) {
    int count = sizeof(kPositionAnimationValues) / sizeof(kPositionAnimationValues[0]);
    NSMutableArray *animationValuesArray = NSMutableArray.array;
    for (int i = 0; i < count; i++) {
        CGFloat rawValue = kPositionAnimationValues[i];
        CGFloat variedValue = rawValue + (rawValue * appliedVariance);
        [animationValuesArray addObject:@(variedValue)];
    }
    return [animationValuesArray copy];
}

static NSArray* processedAnimationKeyTimes () {
    CGFloat random = arc4random_uniform(8)/100.f;
    int count = sizeof(kPositionAnimationKeyTimes) / sizeof(kPositionAnimationKeyTimes[0]);
    NSMutableArray *animationKeyTimesArray = NSMutableArray.array;
    for (int i = 0; i < count; i++) {
        CGFloat rawValue = kPositionAnimationKeyTimes[i];
        CGFloat variedValue = rawValue;
        if (rawValue != 0 && rawValue != 1) {
            int sign = arc4random_uniform(2) == 1 ? 1 : (-1);
            variedValue += (sign * random);
            variedValue = MIN(variedValue, 0.99f);
            variedValue = MAX(variedValue, 0.01f);
        }
        [animationKeyTimesArray addObject:@(variedValue)];
    }
    return [animationKeyTimesArray copy];
}

- (BOOL)isWiggling {
    for (NSString *animationKeys in @[kWiggleRotation,kWigglePosition]) {
        if ([self.layer.animationKeys containsObject:animationKeys]) {
            return YES;
        }
    }
    return NO;
}

- (void)endWiggling {
    for (NSString *wiggleAnimationKey in wiggleAnimations()) {
        [self.layer removeAnimationForKey:wiggleAnimationKey];
    }
}

static NSArray* wiggleAnimations () {
    return @[
             kWiggleRotation,
             kWigglePosition
             ];
}

@end