POP

一、简介

POP 动画极为流畅，其秘密就在于这个 Engine 中的POPAnimator 里，POP 通过 CADisplayLink 高达 60 FPS 的特性，打造了一个游戏级的动画引擎。
源码：https://github.com/facebook/pop

二、基本用法

POPSpringAnimation 有弹性效果的动画类（个人比较喜欢这个）
POPBasicAnimation 基本动画类
POPDecayAnimation 衰减动画类
POPCustomAnimation 可以自定义动画的类
1.POPBasicAnimation

NSInteger height = CGRectGetHeight(self.view.bounds); 
NSInteger width = CGRectGetWidth(self.view.bounds); 
 
CGFloat centerX = arc4random() % width; 
CGFloat centerY = arc4random() % height; 
 
POPBasicAnimation *anim = [POPBasicAnimation animationWithPropertyNamed:kPOPViewCenter]; 
anim.toValue = [NSValue valueWithCGPoint:CGPointMake(centerX, centerY)]; 
anim.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut]; 
anim.duration = 0.4; 
[self.testView pop_addAnimation:anim forKey:@"centerAnimation"];

2.POPSpringAnimation

1.springBounciness 弹簧弹力 取值范围为[0, 20]，默认值为4
2.springSpeed 弹簧速度，速度越快，动画时间越短 [0, 20]，默认为12，和springBounciness一起决定着弹簧动画的效果
3.dynamicsTension 弹簧的张力
4.dynamicsFriction 弹簧摩擦
5.dynamicsMass 质量 。张力，摩擦，质量这三者可以从更细的粒度上替代springBounciness和springSpeed
POPSpringAnimation *anim = [POPSpringAnimation animationWithPropertyNamed:kPOPViewCenter]; 
 
NSInteger height = CGRectGetHeight(self.view.bounds); 
NSInteger width = CGRectGetWidth(self.view.bounds); 
 
CGFloat centerX = arc4random() % width; 
CGFloat centerY = arc4random() % height; 
 
anim.toValue = [NSValue valueWithCGPoint:CGPointMake(centerX, centerY)]; 
anim.springBounciness = 16; 
anim.springSpeed = 6; 
[self.testView pop_addAnimation:anim forKey:@"center"]; 

3.POPDecayAnimation

velocity 也是必须和你操作的属性有相同的结构，如果你操作的是 bounds，想实现一个水滴滴到桌面的扩散效果，那么应该是 [NSValue valueWithCGRect:CGRectMake(0, 0,20.0, 20.0)]
如果 velocity 是负值，那么就会反向递减。
deceleration （负加速度） 是一个你会很少用到的值，默认是就是我们地球的 0.998

POPDecayAnimation *anim = [POPDecayAnimation animWithPropertyNamed:kPOPLayerPositionX]; 
anim.velocity = @(100.0); 
anim.fromValue =  @(25.0); 
//anim.deceleration = 0.998; 
anim.completionBlock = ^(POPAnimation *anim, BOOL finished) { 
  if (finished) {NSLog(@"Stop!");}}; 

三、发布界面的弹出效果

#import "XMGPublishViewController.h"
#import "TWVerticalButton.h"
#import "TWPostWordViewController.h"
#import "TWPostBlogViewController.h"
#import "TWPostPictureViewController.h"
#import "TWNavigationController.h"
#import 
#import 
#import 

static CGFloat const XMGAnimationDelay = 0.1;
static CGFloat const XMGSpringFactor = 10;

@interface XMGPublishViewController ()
@end

@implementation XMGPublishViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self cheakNetworkStatus];
    // 让控制器的view不能被点击
    self.view.userInteractionEnabled = NO;
    
    // 数据
    NSArray *images = @[@"publish-text", @"publish-picture", @"publish-text"];
    NSArray *titles = @[@"发说说", @"发图片", @"发日志"];
    
    // 中间的6个按钮
    int maxCols = 3;
    CGFloat buttonW = 72;
    CGFloat buttonH = buttonW + 30;
    CGFloat buttonStartY = (TWScreenH - buttonH) * 0.5;
    CGFloat buttonStartX = 20;
    CGFloat xMargin = (TWScreenW - 2 * buttonStartX - maxCols * buttonW) / (maxCols - 1);
    for (int i = 0; i