PeriscopeHeartAnimation

//
//  ViewController.m
//  PeriscopeHeartAnimation
//
//  Created by ldj on 4/28/15.
//  Copyright (c) 2015 ldj. All rights reserved.
//

#import "ViewController.h"

#define kScreenWidth [[UIScreen mainScreen] bounds].size.width
#define kScreenHeight [[UIScreen mainScreen] bounds].size.height

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(addHeart)];
    [self.view addGestureRecognizer:tap];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

- (void)addHeart {
    UIImageView *heartImageView = [[UIImageView alloc] initWithFrame:CGRectMake(kScreenWidth / 2.0 - 14, kScreenHeight - 100, 28, 26)];

    heartImageView.image = [UIImage imageNamed:@"heart"];
    heartImageView.transform = CGAffineTransformMakeScale(0, 0);
    [self.view addSubview:heartImageView];

    CGFloat duration = 5 + (arc4random() % 5 - 2);
    [UIView animateWithDuration:0.3 animations:^{
        heartImageView.transform = CGAffineTransformMakeScale(1, 1);
        heartImageView.transform = CGAffineTransformMakeRotation(-0.01 * (arc4random() % 20));
    }];
    [UIView animateWithDuration:duration animations:^{
        heartImageView.alpha = 0;
    }];
    CAKeyframeAnimation *animation = [self createAnimation:heartImageView.frame];
    animation.duration = duration;
    [heartImageView.layer addAnimation:animation forKey:@"position"];
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)((duration + 0.5) * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [heartImageView removeFromSuperview];
    });
}

- (CAKeyframeAnimation *)createAnimation:(CGRect)frame {
    CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    CGMutablePathRef path = CGPathCreateMutable();

    int height = -100 + arc4random() % 40 - 20;
    int xOffset = frame.origin.x;
    int yOffset = frame.origin.y;
    int waveWidth = 50;
    CGPoint p1 = CGPointMake(xOffset, height * 0 + yOffset);
    CGPoint p2 = CGPointMake(xOffset, height * 1 + yOffset);
    CGPoint p3 = CGPointMake(xOffset, height * 2 + yOffset);
    CGPoint p4 = CGPointMake(xOffset, height * 2 + yOffset);

    CGPathMoveToPoint(path, NULL, p1.x,p1.y);

    if (arc4random() % 2) {
        CGPathAddQuadCurveToPoint(path, NULL, p1.x - arc4random() % waveWidth, p1.y + height / 2.0, p2.x, p2.y);
        CGPathAddQuadCurveToPoint(path, NULL, p2.x + arc4random() % waveWidth, p2.y + height / 2.0, p3.x, p3.y);
        CGPathAddQuadCurveToPoint(path, NULL, p3.x - arc4random() % waveWidth, p3.y + height / 2.0, p4.x, p4.y);
    } else {
        CGPathAddQuadCurveToPoint(path, NULL, p1.x + arc4random() % waveWidth, p1.y + height / 2.0, p2.x, p2.y);
        CGPathAddQuadCurveToPoint(path, NULL, p2.x - arc4random() % waveWidth, p2.y + height / 2.0, p3.x, p3.y);
        CGPathAddQuadCurveToPoint(path, NULL, p3.x + arc4random() % waveWidth, p3.y + height / 2.0, p4.x, p4.y);
    }
    animation.path = path;
    animation.calculationMode = kCAAnimationCubicPaced;
    CGPathRelease(path);
    return animation;
}

@end