IOS的处理touch事件处理(依照手指的移动移动一个圆,开发环境用的ios7,storyboard）

首先定义这个ball它有两个属性和两个方法：

 

@property(nonatomic) CGPoint location;

@property(nonatomic) CGFloat length;

-(CGPoint) getCenterPoint;

-(BOOL) isInTheBall:(CGPoint) point;

方法体是：

//找出ball的中心点  
-(CGPoint) getCenterPoint {  
      
    return CGPointMake((self.location.x+self.length/2), self.location.y+self.length/2);  
};  
  
  
//看点point是不是在ball的范围内  
-(BOOL) isInTheBall:(CGPoint) point{  
    CGPoint center = self.getCenterPoint;  
    float t = (point.x - center.x) * (point.x - center.x);  
    float y = (point.y - center.y) * (point.y - center.y);  
      
    float k = sqrtf(t+y);  
    if (k < self.length/2) {  
        return YES;  
    }else {  
        return NO;  
    }  
};  

 

定义BallView继承UIView

@property(nonatomic) Ball* ball;  
@property(nonatomic) BOOL isTouch;  //表示手指在ball的范围内移动  
@property(nonatomic) CGPoint prePoint;  //手指在进入move事件之前的那个点  
- (id)initWithBall:(CGRect)frame aBall:(Ball*) ball; //初始化方法  

 

初始化函数为:

- (id)initWithBall:(CGRect)frame aBall:(Ball*) ball  
{  
    self = [super initWithFrame:frame];  
    if (self) {  
        // Initialization code  
        self.ball = ball;  
    }  
    return self;  
}  
  
-(void)awakeFromNib{  
    self.backgroundColor = nil;  
    self.opaque = NO;  
}  
  
// Only override drawRect: if you perform custom drawing.  
// An empty implementation adversely affects performance during animation.  
- (void)drawRect:(CGRect)rect  
{  
    // Drawing code  
    [super drawRect:rect];  
      
    CGContextRef contextRef = UIGraphicsGetCurrentContext();  
    [[UIColor whiteColor] set];  
      
    //rect是整个view  
    CGContextFillRect(contextRef, rect);  
      
    [[UIColor redColor] set];  
      
    //CGContextAddEllipseInRect不会填充圆圈的内部  
   // CGContextAddEllipseInRect(contextRef, CGRectMake(200.0f, 200.0f, 50.0f, 50.0f));  
    CGContextFillEllipseInRect(contextRef, CGRectMake(self.ball.location.x,self.ball.location.y,self.ball.length,self.ball.length));  
      
    CGContextStrokePath(contextRef);  
}  

 

我们在viewController里初始化只要：

-(void) loadView{  
    [super loadView];  
  
    Ball* ball = [[Ball alloc] init];  
    ball.location = CGPointMake(200.0f, 100.0f);  
    ball.length = 80.0f;  
    BallView* view = [[BallView alloc] initWithBall:[UIScreen mainScreen].bounds aBall:ball];  
    [self.view addSubview:view];  
      
      
}  

 

然后在下面在BallView中进行事件处理

-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{  
    NSLog(@"touchesBegan");  
    //下面两句知道手指在屏幕上的点的信息  
    UITouch* touch = [touches anyObject];  
    CGPoint point = [touch locationInView:self];  
      
    if ([self.ball isInTheBall:point]) {  
        self.isTouch = YES;  
        self.prePoint = point;  
    }else{  
        self.isTouch = NO;  
    }  
    NSLog(@"x=%f,y=%f",point.x,point.y);  
}  
  
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{  
     NSLog(@"touchesMoved");  
    if (self.isTouch) {  
          
        CGRect preRect = CGRectMake(self.ball.location.x, self.ball.location.y, self.ball.length, self.ball.length);  
        //先用之前的location绘制一遍  
        [self setNeedsDisplayInRect:preRect];  
          
        UITouch* touch = [touches anyObject];  
        CGPoint point = [touch locationInView:self];  
          
        //cx和cy是手指的偏移量，用他们可以计算出新的location  
        float cx = point.x - self.prePoint.x;  
        float cy = point.y - self.prePoint.y;  
          
        self.ball.location = CGPointMake(self.ball.location.x + cx, self.ball.location.y+cy);  
        CGRect newRect = CGRectMake(self.ball.location.x, self.ball.location.y, self.ball.length, self.ball.length);  
        //用新的location绘制一遍  
        [self setNeedsDisplayInRect:newRect];  
        self.prePoint = point;  
    }  
}  
  
  
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{  
    NSLog(@"touchesEnded");  
    self.isTouch = NO;  
}