iOS实现大雪纷飞动画

本文实例为大家分享了ios实现大雪纷飞动画的具体代码，供大家参考，具体内容如下

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];
  }];
}

4.demo也不能少

下载地址：snow

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。