本文实例为大家分享了IOSdrawRect实现雪花飘落效果的具体代码，供大家参考，具体内容如下
绘制原理：
雪花效果最主要的思路就是在于循环产生带雪花图片的imageView, 产生的雪花的imageview的 x、y、宽、下落的速度都是随机的，这个可以用随机数来产生数据。
实现代码：
#import <UIKit/UIKit.h> @interface HHFSnowflakeFallingView : UIView /** * 快速创建一个雪花飘落效果的view * * @param bgImageName 背景图片的名称 * @param snowImageName 雪花图片的名称 * @param frame frame * * @return 实例化的 雪花飘落效果的view */ @property(nonatomic,strong) UIImageView *bgImageView; @property(nonatomic,copy) NSString *snowImgName; + (instancetype) snowfladeFallingViewWithBackgroundImageName:(NSString *) bgImageName snowImageName:(NSString *)snowImageName initWithFrame:(CGRect)frame; + //开始下雪 - (void) beginShow; @end
#import "HHFSnowflakeFallingView.h"
@implementation HHFSnowflakeFallingView
/**
* <#Description#>
*
* @param bgImageName bgImageName 背景图片
* @param snowImageName snowImageName 雪花图片
* @param frame frame 视图的位置和大小
*
* @return view 需要绘制的视图
*/
+ (instancetype) snowfladeFallingViewWithBackgroundImageName:(NSString *) bgImageName snowImageName:(NSString *)snowImageName initWithFrame:(CGRect)frame{
HHFSnowflakeFallingView *view = [[HHFSnowflakeFallingView alloc] initWithFrame:frame];
view.bgImageView.image = [UIImage imageNamed:bgImageName];
view.snowImgName = snowImageName;
return view;
}
- (instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
self.clipsToBounds = YES;
//添加背景图片的imageview
self.bgImageView = [[UIImageView alloc] init];
self.bgImageView.frame = self.bounds;
self.bgImageView.contentMode = UIViewContentModeScaleAspectFill;
[self addSubview:self.bgImageView];
}
return self;
}
//开始下雪
- (void) beginShow{
//启动定时器,使得一直调用setNeedsDisplay从而调用- (void) drawRect:(CGRect )rect
//不得手动调用- (void) drawRect:(CGRect )rect
CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(setNeedsDisplay)];
//让定时器循环调用
[link addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
}
- (void) drawRect:(CGRect)rect {
//控制雪花最多的个数
if (self.subviews.count >250) {
return;
}
//雪花的宽度
int width = arc4random() % 20;
while (width < 5) {
width = arc4random() % 20;
}
//雪花的速度
int speed = arc4random() % 15;
while (speed < 5) {
speed = arc4random() % 15;
}
//雪花起点y
int startY = - (arc4random() % 100);
//雪花起点x
int startX = arc4random() % (int) [UIScreen mainScreen].bounds.size.width;
//雪花终点x
int endX = arc4random() % (int) [UIScreen mainScreen].bounds.size.width;
UIImageView *imageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:self.snowImgName]];
imageView.frame = CGRectMake(startX, startY, width, width);
[self addSubview:imageView];
//设置动画
[UIView animateWithDuration:speed animations:^{
//设置雪花最终的frame
imageView.frame = CGRectMake(endX, [UIScreen mainScreen].bounds.size.height, width, width);
//设置雪花的旋转
imageView.transform = CGAffineTransformRotate(imageView.transform, M_PI);
//设置雪花透明度,使得雪花快落地的时候就像快消失的一样
imageView.alpha = 0.3;
} completion:^(BOOL finished) {
[imageView removeFromSuperview];
}];
}
@end
#import "ViewController.h"
#import "HHFSnowflakeFallingView.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
/**
雪花效果最主要的思路就是在于循环产生带雪花图片的imageView, 产生的雪花的imageview的 x、y、宽、下落的速度都是随机的，这个可以用随机数来产生数据。
*/
self.navigationItem.title = @"雪花飘落效果";
//创建雪花飘落效果的view
HHFSnowflakeFallingView *snowflakeFallingView = [HHFSnowflakeFallingView snowfladeFallingViewWithBackgroundImageName:@"snow_background" snowImageName:@"snow" initWithFrame:self.view.bounds];
//开始下雪
[snowflakeFallingView beginShow];
[self.view addSubview:snowflakeFallingView];
}
@end
运行效果:
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。
