通过一条线连接可拖动的移动ui按钮

Question

我如何用一条线连接两个移动(可拖动)ui按钮?

问题:当我连接它看起来很好，但当我试图拖动一个按钮线停留在相同的位置。

我想做一些像发现音乐或发现应用程序，构建移动图形与uibutton作为节点。

下面是我的代码示例:

- (CGRect)currentRect {
return CGRectMake (firstTouch.x,
firstTouch.y,
lastTouch.x - firstTouch.x,
lastTouch.y - firstTouch.y);
}
- (void)drawRect:(CGRect)rect {
self.currentColor = [UIColor redColor];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 2.0);
CGContextSetStrokeColorWithColor(context, currentColor.CGColor);
CGContextSetFillColorWithColor(context, currentColor.CGColor);
CGContextMoveToPoint(context, firstTouch.x, firstTouch.y);
CGContextAddLineToPoint(context, lastTouch.x, lastTouch.y);
CGContextStrokePath(context);
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
firstTouch = [touch locationInView:self];
lastTouch = [touch locationInView:self];
[self setNeedsDisplay];
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
lastTouch = [touch locationInView:self];
redrawRect = CGRectUnion(redrawRect, self.currentRect);
redrawRect = CGRectInset(redrawRect, -2.0, -2.0);
[self setNeedsDisplayInRect:redrawRect];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
lastTouch = [touch locationInView:self];
redrawRect = CGRectUnion(redrawRect, self.currentRect);
[self setNeedsDisplayInRect:redrawRect];
}

截图

Answer 1

你应该先清除上下文。试一试:

- (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [[UIColor blackColor] CGColor]);
    CGContextFillRect(context, self.bounds);
    self.currentColor = [UIColor redColor];
    CGContextSetLineWidth(context, 2.0);
    CGContextSetStrokeColorWithColor(context, currentColor.CGColor);
    //...

我没有测试代码，但它应该有帮助