iOS粒子路径移动效果 iOS实现QQ拖动效果

//获取两个圆之间的距离
CGFloat distance = [self distanceWithSmallCircle:self.smallCircle bigCircle:self];
if(distance<=MAX_DIST){//只有距离不超过最大距离才计算小圆半径
 //计算小圆的半径
 //小圆半径最小的时候是MIN_RADIUS,这个时候两个圆达到最大距离MAX_DIST
 //小圆半径最大的时候是原始半径，这个时候两圆距离是0
 //处于前面两者之间的时候，小圆的半径是：MIN_RADIUS + (原始半径 - MIN_RADIUS)/MAX_DIST * （MAX_DIST - 当前的距离）
 CGFloat smallR = self.bounds.size.width * 0.5;
 smallR = MIN_RADIUS + (MAX_DIST-distance) * (smallR-MIN_RADIUS)/MAX_DIST;
 //重新设置小圆的尺寸
 self.smallCircle.bounds = CGRectMake(0, 0, smallR*2, smallR*2);
 //重新设置小圆的半径
 self.smallCircle.layer.cornerRadius = smallR;
}else{//超过了最大距离
 self.smallCircle.hidden = YES;
}

//
// BageValueView.m
// 03_UIView78_粒子效果2
//
// Created by 杞文明 on 17/7/22.
// Copyright © 2017年 杞文明. All rights reserved.
//

#import "BageValueView.h"

#define MAX_DIST 80
#define MIN_RADIUS 5
@interface BageValueView()

@property (nonatomic, weak) UIView *smallCircle;
@property (nonatomic, weak) CAShapeLayer *shap;


@end

@implementation BageValueView

-(void)awakeFromNib{
 [self setUp];
}

-(instancetype)initWithFrame:(CGRect)frame{
 if ( self = [super initWithFrame:frame] ) {
  [self setUp];
 }
 return self;
}

//形状图层
-(CAShapeLayer*)shap{
 if(_shap == nil){
  //形状图层，它可以根据一个路径生成一个形状
  CAShapeLayer *shap = [CAShapeLayer layer];
  //设置形状填充色
  shap.fillColor = [UIColor redColor].CGColor;
  _shap = shap;
  //添加到最底层
  [self.superview.layer insertSublayer:shap atIndex:0];
 }
 return _shap;
}

//初始化
-(void)setUp{
 //设置圆角
 self.layer.cornerRadius = self.bounds.size.width * 0.5;

 //设置背景文字颜色
 [self setBackgroundColor:[UIColor redColor]];
 [self setTitleColor:[UIColor whiteColor] forState:UIControlStateNormal];
 self.titleLabel.font = [UIFont systemFontOfSize:12];

 //添加手势
 UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
 [self addGestureRecognizer:pan];

 //添加小圆
 UIView *smallCircle = [[UIView alloc]initWithFrame:self.frame];
 smallCircle.backgroundColor = self.backgroundColor;
 smallCircle.layer.cornerRadius = self.layer.cornerRadius;
 self.smallCircle = smallCircle;
 //把小圆添加到父控件中，并且在大圆下面
 [self.superview insertSubview:smallCircle belowSubview:self];

}

-(void)pan:(UIPanGestureRecognizer*)pan{
 //获取当前点
 CGPoint currentP = [pan translationInView:self];
 //移动
 CGPoint center = self.center;
 center.x += currentP.x;
 center.y += currentP.y;
 self.center = center;
 //复位
 [pan setTranslation:CGPointZero inView:self];

 //获取两个圆之间的距离
 CGFloat distance = [self distanceWithSmallCircle:self.smallCircle bigCircle:self];
 if(distance<=MAX_DIST){//只有距离不超过最大距离才计算小圆半径
  //计算小圆的半径
  //小圆半径最小的时候是MIN_RADIUS,这个时候两个圆达到最大距离MAX_DIST
  //小圆半径最大的时候是原始半径，这个时候两圆距离是0
  //处于前面两者之间的时候，小圆的半径是：MIN_RADIUS + (原始半径 - MIN_RADIUS)/MAX_DIST * （MAX_DIST - 当前的距离）
  CGFloat smallR = self.bounds.size.width * 0.5;
  smallR = MIN_RADIUS + (MAX_DIST-distance) * (smallR-MIN_RADIUS)/MAX_DIST;
  //重新设置小圆的尺寸
  self.smallCircle.bounds = CGRectMake(0, 0, smallR*2, smallR*2);
  //重新设置小圆的半径
  self.smallCircle.layer.cornerRadius = smallR;
 }else{//超过了最大距离
  self.smallCircle.hidden = YES;
  [self.shap removeFromSuperlayer];
 }

 //创建不规则路径，其实就是连个圆之间连接的部分
 //小圆不隐藏才创建
 if(self.smallCircle.hidden == NO){
  UIBezierPath *path = [self pathWithSmallCircle:self.smallCircle bigCircle:self];
  self.shap.path = path.CGPath;
 }

 //当手指松开的时候
 if (pan.state==UIGestureRecognizerStateEnded) {
  //如果两圆之间的距离小于最大距离，大圆复位
  if (distance<MAX_DIST) {
   //移除形状图层
   [self.shap removeFromSuperlayer];
   //添加一个弹性动画
   [UIView animateWithDuration:0.25 delay:0 usingSpringWithDamping:0.2 initialSpringVelocity:0 options:UIViewAnimationOptionCurveLinear animations:^{
    //大圆复位
    self.center = self.smallCircle.center;
   } completion:^(BOOL finished) {
    //小圆显示
    self.smallCircle.hidden = NO;
   }];
  } else {
   //距离大于最大位置的时候，播放动画，按钮从父控件中删除
   //添加一个UIImageView 用来播放动画
   UIImageView *imageV = [[UIImageView alloc] initWithFrame:self.bounds];
   [self addSubview:imageV];

   //添加图片
   NSMutableArray *imageArray = [NSMutableArray array];
   for (int i=1; i<=8; i++) {
    NSString *imageName = [NSString stringWithFormat:@"%d",i];
    UIImage *image = [UIImage imageNamed:imageName];
    [imageArray addObject:image];
   }
   imageV.animationImages = imageArray;
   //设置动画时长
   [imageV setAnimationDuration:1];
   //开始动画
   [imageV startAnimating];

   //一秒钟后.把当前的按钮从父控件当中移.
   dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
    [self removeFromSuperview];
   });
  }
 }
}

//计算两个圆之间的距离 使用勾股定理：两直角边的平方和等于斜边的平方
- (CGFloat)distanceWithSmallCircle:(UIView *)smallCircle bigCircle:(UIView *)bigCircle{
 //X轴上的偏移量（就是x1-x2的值）
 CGFloat offsetX = bigCircle.center.x - smallCircle.center.x;
 //y轴上的偏移量（就是y1-y2的值）
 CGFloat offsetY = bigCircle.center.y - smallCircle.center.y;

 return sqrt(offsetX*offsetX + offsetY*offsetY);
}

//根据两个圆设置一个不规的路径
- (UIBezierPath *)pathWithSmallCircle:(UIView *)smallCircle bigCircle:(UIView *)bigCircle{

 CGFloat x1 = smallCircle.center.x;
 CGFloat y1 = smallCircle.center.y;

 CGFloat x2 = bigCircle.center.x;
 CGFloat y2 = bigCircle.center.y;

 CGFloat d = [self distanceWithSmallCircle:smallCircle bigCircle:self];

 if (d <= 0) {
  return nil;
 }


 CGFloat cosθ = (y2 - y1) / d;
 CGFloat sinθ = (x2 - x1) / d;

 CGFloat r1 = smallCircle.bounds.size.width * 0.5;
 CGFloat r2 = bigCircle.bounds.size.width * 0.5;

 CGPoint pointA = CGPointMake(x1 - r1 * cosθ, y1 + r1 * sinθ);
 CGPoint pointB = CGPointMake(x1 + r1 * cosθ, y1 - r1 * sinθ);
 CGPoint pointC = CGPointMake(x2 + r2 * cosθ, y2 - r2 * sinθ);
 CGPoint pointD = CGPointMake(x2 - r2 * cosθ, y2 + r2 * sinθ);
 CGPoint pointO = CGPointMake(pointA.x + d * 0.5 * sinθ, pointA.y + d * 0.5 * cosθ);
 CGPoint pointP = CGPointMake(pointB.x + d * 0.5 * sinθ, pointB.y + d * 0.5 * cosθ);


 UIBezierPath *path = [UIBezierPath bezierPath];
 //AB
 [path moveToPoint:pointA];
 [path addLineToPoint:pointB];
 //BC(曲线)
 [path addQuadCurveToPoint:pointC controlPoint:pointP];
 //CD
 [path addLineToPoint:pointD];
 //DA(曲线)
 [path addQuadCurveToPoint:pointA controlPoint:pointO];

 return path;

}


//清空高亮状态
-(void)setHighlighted:(BOOL)highlighted{}

@end

//
// ViewController.m
// 03_UIView78_粒子效果2
//
// Created by 杞文明 on 17/7/22.
// Copyright © 2017年 杞文明. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
 [super viewDidLoad];
 //让View在显示时不要把Autoresizing转成自动布局
 self.view.translatesAutoresizingMaskIntoConstraints = NO;
}


@end