IOS中一个简单的粒子效果实现

//
// DrawView.m
// 06-粒子效果
//
// Created by xgao on 16/11/24.
// Copyright (c) 2016年 xgao. All rights reserved.
//#import "DrawView.h"// 复制的实例个数
static int _instansCount = ;@interface DrawView ()@property (nonatomic, strong) UIBezierPath *path;@property (nonatomic, weak) CALayer *dotLayer;@property (nonatomic, weak) CAReplicatorLayer *repL;@end@implementation DrawView#pragma mark - 懒加载点层
- (CALayer *)dotLayer{ if (_dotLayer == nil) {
// 创建图层
CALayer *layer = [CALayer layer]; CGFloat wh = ;
layer.frame = CGRectMake(, -, wh, wh);
layer.cornerRadius = wh / ;
layer.backgroundColor = [UIColor blueColor].CGColor;
// 将layer添加到CAReplicatorLayer中
[_repL addSublayer:layer]; _dotLayer = layer;
}
return _dotLayer;
}- (UIBezierPath *)path{ if (_path == nil) {
_path = [UIBezierPath bezierPath];
} return _path;
}#pragma mark - 开始点击调用// 鼠标开始点击
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{ // 获取touch对象
UITouch *touch = [touches anyObject];
// 获取当前触摸点
CGPoint curP = [touch locationInView:self]; // 设置起点
[self.path moveToPoint:curP];
}// 鼠标按住移动
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ // 获取touch对象
UITouch *touch = [touches anyObject];
// 获取当前触摸点
CGPoint curP = [touch locationInView:self]; // 添加线到某个点
[_path addLineToPoint:curP]; // 重绘
[self setNeedsDisplay]; _instansCount ++;
}- (void)drawRect:(CGRect)rect { // 进行路径线条的绘制
[_path stroke];
}#pragma mark - 开始动画
- (void)startAnim{ // 创建帧动画
CAKeyframeAnimation *anim = [CAKeyframeAnimation animation];
anim.keyPath = @"position";
anim.path = _path.CGPath;
anim.duration = ;
anim.repeatCount = MAXFLOAT;
[self.dotLayer addAnimation:anim forKey:nil]; // 注意:如果复制的子层有动画，先添加动画，再复制
// 复制子层
_repL.instanceCount = _instansCount; // 延迟图层动画
_repL.instanceDelay = 0.2;}#pragma mark - 加载完xib调用，创建复制层
- (void)awakeFromNib{ // 创建复制层
CAReplicatorLayer *repL = [CAReplicatorLayer layer];
repL.frame = self.bounds;
[self.layer addSublayer:repL]; _repL = repL;
}#pragma mark - 重绘
- (void)reDraw{ // 清空绘图信息
_path = nil;
[self setNeedsDisplay]; // 把图层移除父控件，复制层也会移除。
[_dotLayer removeFromSuperlayer];
_dotLayer = nil; // 清空子层总数
_instansCount = ;
}
@end

// 点击开始动画
- (IBAction)startAnim:(id)sender { DrawView *view = (DrawView *)self.view;
[view startAnim];}// 重置按钮
- (IBAction)reDraw:(id)sender { DrawView *view = (DrawView *)self.view;
[view reDraw];
}