连接通过线连接的可拖动移动 UI 按钮

Question

如何用一条线连接两个移动（可拖动）UIButton？

问题：当我连接时，它看起来相当不错，但是当我尝试拖动一个按钮时，该线保持在相同的位置。

我想做一些类似发现音乐或发现应用程序的事情，以 UIButtons 作为节点构建移动图表。

这是我的代码示例：

- (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];
}

屏幕截图

Answer 1

你应该先弄清楚上下文。尝试：

- (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);
    //...

我还没有测试过代码，但它应该有帮助