iOS实现浮动泡泡功能，悬浮泡泡，windows系统屏幕保护程序的气泡功能(碰撞检测)

使用到的知识点有

1.block封装NSTimer

2.随机生成0-X之间的正数

3.两个frame是否有交集:CGRectIntersectsRect

4.随机生成-1~1之间的浮点数

5.CGPoint存储在NSArray里，从NSArray里读取

6.计算两个point的距离(碰撞检测)

类似的效果：打方块，台球。

效果图

开始

1.随机生成三个中心点坐标，三个移动方向。要求：在屏幕范围内 、三个btn没有交集

    __block BOOL isX = NO;
    
    int width = SCREEN_WIDTH_NEW;
    int height = SCREEN_HEIGHT_NEW;
    
    NSMutableArray *ballArray = [[NSMutableArray alloc]initWithCapacity:3];
    NSMutableArray *ballDirectionArray = [[NSMutableArray alloc]initWithCapacity:3];
    
    
    for (int i = 0; i < 3; i++) {
        //随机生成3个center
        
        BOOL qualified = NO;
        
        int cx = 0;
        int cy = 0;
        
        while (!qualified) {
            
            cx = arc4random() % width;
            cy = arc4random() % height;
            
            
            //不重叠
            BOOL containsPoint = NO;
            for (int j = 0; j < ballArray.count; j++) {
                
                UIButton *btnn = ballArray[j];
                
                if (CGRectIntersectsRect(btnn.frame,CGRectMake(cx  , cy  , BALL_WIDTH, BALL_WIDTH))) {
                    containsPoint = YES;
                }
            }
            
            //在屏幕范围内
            if (cx > BALL_WIDTH && cy > BALL_WIDTH  && cx < SCREEN_WIDTH_NEW - BALL_WIDTH  && cy < SCREEN_WIDTH_NEW - BALL_WIDTH && containsPoint == NO) {
                
                qualified = YES;
            }else{
                continue;
            }
            
            UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
            [btn setImage:[UIImage imageNamed:[NSString stringWithFormat:@"0%ddog",i]] forState:UIControlStateNormal];
            //btn.backgroundColor = [UIColor redColor];
            btn.centerY = cy;
            btn.centerX = cx;
            btn.width = 70;
            btn.height = 70;
            [self.view addSubview:btn];
            
            [ballArray addObject:btn];
            
            NSLog(@"%@ %@",NSStringFromCGRect(btn.frame) ,NSStringFromCGRect( CGRectMake(cx  , cy  , BALL_WIDTH, BALL_WIDTH)));
            
        }
        
        
        
        //随机生成3个移动方向
        double randomX = (double)arc4random() / ARC4RAND_MAX * 2.0f - 1.0f;
        double randomY = (double)arc4random() / ARC4RAND_MAX * 2.0f - 1.0f;
        NSLog(@"%f %f",randomX,randomY);
        
        [ballDirectionArray addObject:[NSValue valueWithCGPoint:CGPointMake(randomX, randomY)]];
        
        
        
    }

2.使用定时器使其“漂浮”并且碰到屏幕边缘或其他的btn要弹回

    
    //    0.03
    //>ios10
    //    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.003 repeats:YES block:^(NSTimer * _Nonnull timer) {
    
    //        <ios10
    NSTimer *timerL = [NSTimer scheduledTimerWithTimeInterval:0.003 block:^{
        
        
        
        for (int j = 0; j < ballArray.count; j++) {
            UIButton *btn = ballArray[j];
            NSValue *val = [ballDirectionArray objectAtIndex:j];
            CGPoint p = [val CGPointValue];
            
            //移动方向
            __block  float vx = p.x;
            __block float vy = p.y;
            
            //掉头
            if (btn.right > SCREEN_WIDTH_NEW  || btn.left < 0) {
                vx = -vx;
                CGPoint p = [val CGPointValue];
                p.x = vx;
                [ballDirectionArray setObject:[NSValue valueWithCGPoint:p] atIndexedSubscript:j];
            }
            if (btn.bottom > SCREEN_HEIGHT_NEW || btn.top <0) {
                vy = -vy;
                CGPoint p = [val CGPointValue];
                p.y = vy;
                [ballDirectionArray setObject:[NSValue valueWithCGPoint:p] atIndexedSubscript:j];
            }
            
            //设置移动方向
            btn.centerX += vx;
            btn.centerY += vy;
            
            //和其他2个按钮比较(碰撞检测)
            for(int k = 0 ; k < 3; k++){
                UIButton *otherbtn = ballArray[k];
                
                //和其他2个按钮比较
                if (btn != otherbtn) {
                    //注意方形和圆形
                    float distance = sqrt(pow((btn.centerX - otherbtn.centerX), 2) + pow((btn.centerY - otherbtn.centerY), 2));
                    
                    if(distance <= BALL_WIDTH){
                        NSValue *valk = [ballDirectionArray objectAtIndex:k];
                        CGPoint pk = [valk CGPointValue];
                        if (isX == NO) {
                            pk.y = -pk.y;
                            //                            isX = !isX;
                        }else{
                            pk.x = -pk.x;
                            //                            isX = !isX;
                            
                        }
                        
                        [ballDirectionArray setObject:[NSValue valueWithCGPoint:pk] atIndexedSubscript:k];
                        
                        
                        NSValue *valk2 = [ballDirectionArray objectAtIndex:j];
                        CGPoint pk2 = [valk2 CGPointValue];
                        if (isX == YES) {
                            
                            pk2.x = -pk2.x;
                        }else{
                            pk2.y = -pk2.y;
                        }
                        
                        [ballDirectionArray setObject:[NSValue valueWithCGPoint:pk2] atIndexedSubscript:j];
                        
                        isX = !isX;
                        
                    }
                }
                
            }
            
        }
        
    } repeats:YES];
    
    
    //    }];

代码工程：

点击打开链接http://download.csdn.net/detail/qq_15509071/9836118