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：
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#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 |
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#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 |
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#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服务器之家。
原文链接：https://blog.csdn.net/light_of_life/article/details/52185778
