iphone - 在 iOS 上绘制带阴影的矩形

Question

我正在尝试使用 iOS 中的库绘制如下图像；但我不能。

我觉得画起来很容易，但我做不到。完成绘制后，我将在其上放置一个标签。

Answer 1

将其用作您的 drawRect 方法:

- (void)drawRect:(CGRect)rect

    //// General Declarations
    CGContextRef context = UIGraphicsGetCurrentContext();

    //// Shadow Declarations
    UIColor* shadow = [UIColor blackColor];
    CGSize shadowOffset = CGSizeMake(1, 1);
    CGFloat shadowBlurRadius = 2;

    //// Frames
    CGRect frame = rect;

    //// Abstracted Graphic Attributes
    CGRect shadowBoxRect = CGRectMake(CGRectGetMinX(frame) + 0, CGRectGetMinY(frame) + 0, 40, 40);
    CGFloat shadowBoxCornerRadius = 4;


    //// ShadowBox Drawing
    UIBezierPath* shadowBoxPath = [UIBezierPath bezierPathWithRoundedRect: shadowBoxRect cornerRadius: shadowBoxCornerRadius];
    [[UIColor lightGrayColor] setFill];
    [shadowBoxPath fill];

    ////// ShadowBox Inner Shadow
    CGRect shadowBoxBorderRect = CGRectInset([shadowBoxPath bounds], -shadowBlurRadius, -shadowBlurRadius);
    shadowBoxBorderRect = CGRectOffset(shadowBoxBorderRect, -shadowOffset.width, -shadowOffset.height);
    shadowBoxBorderRect = CGRectInset(CGRectUnion(shadowBoxBorderRect, [shadowBoxPath bounds]), -1, -1);

    UIBezierPath* shadowBoxNegativePath = [UIBezierPath bezierPathWithRect: shadowBoxBorderRect];
    [shadowBoxNegativePath appendPath: shadowBoxPath];
    shadowBoxNegativePath.usesEvenOddFillRule = YES;

    CGContextSaveGState(context);
    {
        CGFloat xOffset = shadowOffset.width + round(shadowBoxBorderRect.size.width);
        CGFloat yOffset = shadowOffset.height;
        CGContextSetShadowWithColor(context,
            CGSizeMake(xOffset + copysign(0.1, xOffset), yOffset + copysign(0.1, yOffset)),
            shadowBlurRadius,
            shadow.CGColor);

        [shadowBoxPath addClip];
        CGAffineTransform transform = CGAffineTransformMakeTranslation(-round(shadowBoxBorderRect.size.width), 0);
        [shadowBoxNegativePath applyTransform: transform];
        [[UIColor grayColor] setFill];
        [shadowBoxNegativePath fill];
    }
    CGContextRestoreGState(context);

}