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小编给大家分享一下iOS如何实现大雪纷飞动画,相信大部分人都还不怎么了解,因此分享这篇文章给大家参考一下,希望大家阅读完这篇文章后大有收获,下面让我们一起去了解一下吧!
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1.结果展示
美丽的雪花,勾起了多少美好的回忆。
2.制作思路
其实创作这样一个大学纷飞的场景是十分简单的,简单到你看了教程之后想不会都不行。OK,下面国际惯例,讲解一下思路吧。
1.创建一个数组用来保存大量的雪花
_imagesArray = [[NSMutableArray alloc] init]; for (int i = 0; i < 1000; ++ i) { UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snow"]]; float x = IMAGE_WIDTH; imageView.frame = CGRectMake(IMAGE_X, -30, x, x); imageView.alpha = IMAGE_ALPHA; [self.view addSubview:imageView]; [_imagesArray addObject:imageView]; }
2.使用时钟(CADisplayLink)来控制下雪,为什么不使用NSTimer呢。其实是可以的,只是(CADisplayLink)刷帧更快一些。
//创建时钟,并且添加到主循环中 CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(makeSnow)]; [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
3.下雪,就是把数组当做队列来使用。
每次从数组头部取出一个雪花并且删除其在数组中的占位。
让雪花飘落,通过UIView动画完成frame,transform等改变。
当动画完成之后,将取出的雪花再次放进数组的尾部
- (void)makeSnow { if (_imagesArray.count > 0) { UIImageView *imageView = _imagesArray[0]; [_imagesArray removeObjectAtIndex:0]; [self snowFall:imageView]; } } - (void)snowFall:(UIImageView *)imageView { [UIView animateWithDuration:10 animations:^{ imageView.frame = CGRectMake(imageView.frame.origin.x, Main_Screen_Height, imageView.frame.size.width, imageView.frame.size.height); imageView.transform = CGAffineTransformMakeScale(0.3, 0.3); imageView.transform = CGAffineTransformRotate(imageView.transform, M_PI); } completion:^(BOOL finished) { float x = IMAGE_WIDTH; imageView.frame = CGRectMake(IMAGE_X, -30, x, x); [_imagesArray addObject:imageView]; }]; }
3.有代码有真相
#define IMAGE_X arc4random()%(int)Main_Screen_Width #define IMAGE_ALPHA ((float)(arc4random()%10))/10 #define IMAGE_WIDTH arc4random()%20 + 10 #define PLUS_HEIGHT Main_Screen_Height/25 #define Main_Screen_Height [[UIScreen mainScreen] bounds].size.height #define Main_Screen_Width [[UIScreen mainScreen] bounds].size.width #import "ViewController.h" @interface ViewController () @property (nonatomic ,strong) NSMutableArray *imagesArray; @property (nonatomic , strong) UIImageView *imageView; @end @implementation ViewController - (void)loadView { UIImageView *imageView = [[UIImageView alloc]initWithFrame:[UIScreen mainScreen].bounds]; imageView.image = [UIImage imageNamed:@"backgound.jpg"]; imageView.contentMode = UIViewContentModeScaleAspectFill; self.view = imageView; } - (void)viewDidLoad { [super viewDidLoad]; _imagesArray = [[NSMutableArray alloc] init]; for (int i = 0; i < 1000; ++ i) { UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"snow"]]; float x = IMAGE_WIDTH; imageView.frame = CGRectMake(IMAGE_X, -30, x, x); imageView.alpha = IMAGE_ALPHA; [self.view addSubview:imageView]; [_imagesArray addObject:imageView]; } //创建时钟,并且添加到主循环中 CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(makeSnow)]; [link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode]; } - (void)makeSnow { if (_imagesArray.count > 0) { UIImageView *imageView = _imagesArray[0]; [_imagesArray removeObjectAtIndex:0]; [self snowFall:imageView]; } } - (void)snowFall:(UIImageView *)imageView { [UIView animateWithDuration:10 animations:^{ imageView.frame = CGRectMake(imageView.frame.origin.x, Main_Screen_Height, imageView.frame.size.width, imageView.frame.size.height); imageView.transform = CGAffineTransformMakeScale(0.3, 0.3); imageView.transform = CGAffineTransformRotate(imageView.transform, M_PI); } completion:^(BOOL finished) { float x = IMAGE_WIDTH; imageView.frame = CGRectMake(IMAGE_X, -30, x, x); [_imagesArray addObject:imageView]; }]; }
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