使自定义视图的框架适合在drawRect中绘制的图像

Question

I am drawing a custom shape (pentagon) in drawRect of my custom UIView subclass:

- (void)drawRect:(CGRect)rect {
    UIBezierPath *aPath = [UIBezierPath bezierPath];

    // Set the starting point of the shape.
    [aPath moveToPoint:CGPointMake(100.0, 0.0)];

    // Draw the lines.
    [aPath addLineToPoint:CGPointMake(200.0, 40.0)];
    [aPath addLineToPoint:CGPointMake(160, 140)];
    [aPath addLineToPoint:CGPointMake(40.0, 140)];
    [aPath addLineToPoint:CGPointMake(0.0, 40.0)];
    [aPath closePath];

    [[UIColor blackColor] setStroke];
    [[UIColor redColor] setFill];

    [aPath fill];
    [aPath stroke];
}

When I add the custom drawing to my viewcontroller with:

- (void)viewDidLoad {
    [super viewDidLoad];
    PentagonView *pentagonView = [[PentagonView alloc] initWithFrame:CGRectMake(0, 0, 300, 300)];
    [self.view addSubview:pentagonView];
}

It ends up looking like:

Obviously I know I'm setting my frame to be 300 width/height, but is there a way to do a "size to fit" content on the view's frame after the contents have been drawn?

Answer 1

If you keep a reference to your UIBezierPath , you can call bounds on it to get the bounding rectangle. Override sizeToFit to use it:

- (void)sizeThatFits:(CGSize)size {
  CGSize newSize = CGSizeZero;
  newSize.width = MIN(size.width, CGRectGetMaxX(self.path.bounds));
  newSize.height = MIN(size.height, CGRectGetMaxY(self.path.bounds));
  return newSize;
}

Answer 2

You are kind of doing this backwards. The drawRect: method should draw its contents to fill its current bounds. In other words, don't hardcode any specific coordinates in drawRect: . Calculate them properly based on the current bounds.

If you want the custom view to have a certain size, override the custom view's sizeToFit: method and return the appropriate size.

This way, when client code calls the custom view's sizeToFit method, the view will be sized based on the results of sizeToFit: . Then the drawRect: method will be called and it will draw to fill that size.