iOS飘雪的动画小demo

1 ViewController.h
2 
3 #import <UIKit/UIKit.h>
4 
5 @interface ViewController : UIViewController{
6     UIImage* flakeImage;
7 }
8 - (void)onTimer;
9 @end

 1 ViewController.m
 2 
 3 #import "ViewController.h"
 4 
 5 @interface ViewController ()
 6 
 7 @end
 8 
 9 @implementation ViewController
10 
11 - (void)viewDidLoad
12 {
13     [super viewDidLoad];
14     self.view.backgroundColor = [UIColor colorWithRed:0.5 green:0.5 blue:1.0 alpha:1.0];
15     flakeImage = [UIImage imageNamed:@"2.png"];
16     [NSTimer scheduledTimerWithTimeInterval:(0.05) target:self selector:@selector(onTimer) userInfo:nil repeats:YES];
17 }
18 - (void)onTimer
19 {
20     //创建图像视图对象
21     UIImageView* flakeView = [[UIImageView alloc] initWithImage:flakeImage];
22     
23     int startX = round(random() % 320);
24     int endX = round(random() % 320);
25     double scale = 1 / round(random() % 100) + 1.0;
26     double speed = 1 / round(random() % 100) + 1.0;
27     flakeView.frame = CGRectMake(startX, -100.0, 25.0 * scale, 25.0 * scale);
28     flakeView.alpha = 0.5;
29     [self.view addSubview:flakeView];
30     [UIView beginAnimations:nil context:(__bridge void *)(flakeView)];
31     [UIView setAnimationDuration:5 * speed];
32     flakeView.frame = CGRectMake(endX, 540.0, 25.0 * scale, 25.0 * scale);
33     [UIView commitAnimations];
34     
35 }
36 
37 
38 - (void)didReceiveMemoryWarning
39 {
40     [super didReceiveMemoryWarning];
41     // Dispose of any resources that can be recreated.
42 }

图片素材，通过Main.storyboard设置背景图片