ios15的雪花场景

Xnip2021-12-12_13-42-15.jpg

#import "ViewController.h"
static long steps;
#define degree2angle(angle) ((angle) * M_PI / 180)
@interface ViewController ()
@property(nonatomic,strong)CADisplayLink *timer;
@end

@implementation ViewController

- (void)viewDidLoad {
    self.timer = [CADisplayLink displayLinkWithTarget:self selector:@selector(snow)];
    [self.timer addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
}

//-(void)update{
 //   steps++;
  //  if(steps % 5 == 0){
  //      [self snow];
  //  }
   
//}
-(void)snow{
    UIImage *snowImage  =  [UIImage imageNamed:@"snow"];
    UIImageView *imageView = [[UIImageView alloc] initWithImage:snowImage];
    CGFloat scale = arc4random_uniform(40) / 100.0;
    imageView.transform = CGAffineTransformMakeScale(scale, scale);
    CGSize winSize  = self.view.bounds.size;
    
    CGFloat x = arc4random_uniform(winSize.width);
    CGFloat y = -imageView.bounds.size.height * 0.5;
    imageView.center = CGPointMake(x, y);
    [self.view addSubview:imageView];

    
    [UIView animateWithDuration:10.0F animations:^{
        CGFloat toX = arc4random_uniform(winSize.width);
        CGFloat toY = winSize.height + imageView.bounds.size.height * 0.5;
        imageView.center = CGPointMake(toX, toY);
        imageView.transform = CGAffineTransformRotate(imageView.transform, degree2angle(arc4random_uniform(360)));
        imageView.alpha  = 0.3;
        
        } completion:^(BOOL finished) {
            [imageView removeFromSuperview];
        }];
    
    
}

- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
    [self.timer invalidate];
}

- (BOOL)prefersStatusBarHidden{
    return YES;
}

@end