❄️ 雪花降落
#define SNOWPOSITION (arc4random() % (int)self.view.frame.size.width)
#define SNOWWIDTH (arc4random() % 20 + 10)
@interface XLRightViewController ()
{
NSMutableArray * snowArr;
}
@end
@implementation XLRightViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
-(void)createUI
{
UIImageView * imageView = [[UIImageView alloc]initWithFrame:[UIScreen mainScreen].bounds];
imageView.image = [UIImage imageNamed:@"3.jpg"];
[self.view addSubview:imageView];
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self createUI];
[self createSnowImageView];
}
-(void)createSnowImageView
{
snowArr = [[NSMutableArray alloc]init];
//创建20多雪花 循环利用
for(int i = 0;i < 20;i++)
{
float snowWidth = SNOWWIDTH;
UIImageView * snowImageView = [[UIImageView alloc]initWithFrame:CGRectMake(SNOWPOSITION, -30, snowWidth, snowWidth)];
snowImageView.image = [UIImage imageNamed:@"snow.png"];
//设置雪花的透明度
snowImageView.alpha = (arc4random() % 10)/10.0;
[self.view addSubview:snowImageView];
//将雪花视图添加到数组中 循环利用
[snowArr addObject:snowImageView];
}
[NSTimer scheduledTimerWithTimeInterval:0.3 target:self selector:@selector(makeSnow) userInfo:nil repeats:YES];
}
-(void)makeSnow
{
//为每朵雪花添加tag值
static int index = 0;
if(snowArr.count > 0)
{
//获取数组中第一朵雪花
UIImageView * imageView = (UIImageView *)snowArr[0];
imageView.tag = ++index;
//添加完tag值的这朵雪花 就可以下落了
[self snowDown:imageView];
//从数组中移除该雪花 等待重用
[snowArr removeObject:imageView];
}
}
-(void)snowDown:(UIImageView *)imageView
{
//为协议中的方法传递参与动画的视图的tag值
[UIView beginAnimations:[NSString stringWithFormat:@"%d",imageView.tag] context:nil];
//设置动画的持续时间
[UIView setAnimationDuration:6];
//设置当前视图控制器为UIView动画代理
[UIView setAnimationDelegate:self];
//设置雪花的降落位置及动画停止的方法
imageView.frame = CGRectMake(imageView.frame.origin.x, self.view.frame.size.height, imageView.frame.size.width, imageView.frame.size.height);
//动画停止的方法--------协议中的方法
[UIView setAnimationDidStopSelector:@selector(snowStop:)];
//开始动画
[UIView commitAnimations];
}
-(void)snowStop:(NSString *)imageTag
{
//获取重复利用的雪花
UIImageView * imageView = (UIImageView *)[self.view viewWithTag:[imageTag integerValue]];
float width = SNOWWIDTH;
imageView.frame = CGRectMake(SNOWPOSITION, -30, width, width);
//将雪花添加到数组中
[snowArr addObject:imageView];
}
