Question

我喜欢ipad上tableView的新分组背景颜色。我想在我的分割控制器右侧的UIViewController的背景上使用相同的颜色。

有谁知道这种颜色是什么？它似乎是一个轻微的梯度。

Answer 1

它不是一种颜色，而是带有渐变图像的UIImageView：

UIImageView* imageView = (UIImageView*) self.tableView.backgroundView;
NSString* file = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Test.png"];
NSData* data = UIImagePNGRepresentation(imageView.image);
[data writeToFile:file atomically:YES];

Answer 2

根据Lutz的回答和this question的答案，以下自定义视图控制器代码创建了表视图背景视图的副本。但是，自动旋转存在问题，这将在下面的第二个代码片段中解决。

// You also need to link against QuartzCore.framework
#import <QuartzCore/QuartzCore.h>

- (void) loadView
{
  CGRect mainViewFrame = [self mainViewFrame];
  self.view = [[[UIView alloc] initWithFrame:mainViewFrame] autorelease];
  CAGradientLayer* gradient = [CAGradientLayer layer];
  gradient.frame = self.view.bounds;
  UIColor* startColor = [UIColor colorWithRed:226.0/255.0 green:229.0/255.0 blue:234.0/255.0 alpha:1.0];
  UIColor* endColor = [UIColor colorWithRed:208.0/255.0 green:210.0/255.0 blue:216.0/255.0 alpha:1.0];
  // Cast to (id) is necessary to get rid of a compiler warning
  gradient.colors = [NSArray arrayWithObjects:(id)startColor.CGColor, (id)endColor.CGColor, nil];
  // Inserting at index position 0 ensures that the gradient is drawn
  // in the background even if the view already has subviews or other
  // sublayers
  [view.layer insertSublayer:gradient atIndex:0];

  // add more subviews
}

- (CGRect) mainViewFrame
{
  // add your frame calculating code here
}

- (void) willAnimateRotationToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation duration:(NSTimeInterval)duration
{
  [UIView animateWithDuration:duration
                        delay:0
                      options:UIViewAnimationCurveLinear
                   animations:^{
                     ((CALayer*)[self.view.layer.sublayers objectAtIndex:0]).frame = self.view.bounds;
                   }
                   completion:NULL];
}

上述代码的问题在于，在旋转动画运行时，原始白色背景可以在很短的时间内看到。不幸的是，我对层数没有足够的了解，所以我开始寻找CAGradientLayer的替代方案。我发现了使用渐变图像设置CALayer.contents。

下面的大多数代码都涉及创建作为便利构造函数的输入所需的模式图像，只有这次使用Core Graphics而不是使用CAGradientLayer“手动”绘制渐变。顺便提一下，渐变绘图代码主要基于Ray Wenderlich的Core Graphics 101 tutorial。

#import <QuartzCore/QuartzCore.h>

- (void) loadView
{
  CGRect mainViewFrame = [self mainViewFrame];
  self.view = [[[UIView alloc] initWithFrame:mainViewFrame] autorelease];
  UIColor* startColor = [UIColor colorWithRed:226.0/255.0 green:229.0/255.0 blue:234.0/255.0 alpha:1.0];
  UIColor* endColor = [UIColor colorWithRed:208.0/255.0 green:210.0/255.0 blue:216.0/255.0 alpha:1.0];

  UIImage* backgroundPattern = [self gradientImageWithSize:CGSizeMake(1, mainViewFrame.size.height)
                                                startColor:startColor
                                                  endColor:endColor];
  self.view.layer.contents = (id)backgroundPattern.CGImage;

  // add more subviews
}

- (CGRect) mainViewFrame
{
  // add your frame calculating code here
}

- (UIImage*) gradientImageWithSize:(CGSize)size startColor:(UIColor*)startColor endColor:(UIColor*)endColor
{
  UIGraphicsBeginImageContext(size);
  CGContextRef context = UIGraphicsGetCurrentContext();

  CGRect rect = CGRectMake(0, 0, size.width, size.height);
  [self drawLinearGradientWithContext:context rect:rect startColor:startColor.CGColor endColor:endColor.CGColor];

  UIImage* gradientImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  return gradientImage;
}

- (void) drawLinearGradientWithContext:(CGContextRef)context rect:(CGRect)rect startColor:(CGColorRef)startColor endColor:(CGColorRef)endColor
{
  CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

  CGFloat locations[] = { 0.0, 1.0 };
  NSArray* colors = [NSArray arrayWithObjects:(id)startColor, (id)endColor, nil];
  // NSArray is toll-free bridged, so we can simply cast to CGArrayRef
  CGGradientRef gradient = CGGradientCreateWithColors(colorSpace,
                                                      (CFArrayRef)colors,
                                                      locations);

  // Draw the gradient from top-middle to bottom-middle
  CGPoint startPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMinY(rect));
  CGPoint endPoint = CGPointMake(CGRectGetMidX(rect), CGRectGetMaxY(rect));

  // Remember context so that later on we can undo the clipping we are going to
  // add to the Core Graphics state machine
  CGContextSaveGState(context);
  // Add clipping with the specified rect so that we can simply draw into the
  // specified context without changing anything outside of the rect. With this
  // approach, the caller can give us a context that already has other stuff
  // in it
  CGContextAddRect(context, rect);
  CGContextClip(context);
  // Finally draw the gradient
  CGContextDrawLinearGradient(context, gradient, startPoint, endPoint, 0);
  // Undo clipping
  CGContextRestoreGState(context);

  // Cleanup memory allocated by CGContextDrawLinearGradient()
  CGGradientRelease(gradient);
  // Cleanup memory allocated by CGColorSpaceCreateDeviceRGB()
  CGColorSpaceRelease(colorSpace);
}

我最喜欢这段代码，因为

干净地自动旋转
没有用于处理自动轮播的自定义代码
可以将与梯度相关的函数重构为单独的实用程序类，以使它们更易于重用

Answer 3

[UIColor colorWithRed：0.953 green：0.953 blue：0.953 alpha：1] / ＃f3f3f3 /

Answer 4

这些都是开箱即用的纹理颜色，UIColor上的静态方法：

+ (UIColor *)lightTextColor;                // for a dark background
+ (UIColor *)darkTextColor;                 // for a light background
+ (UIColor *)groupTableViewBackgroundColor;
+ (UIColor *)viewFlipsideBackgroundColor;
+ (UIColor *)scrollViewTexturedBackgroundColor __OSX_AVAILABLE_STARTING(__MAC_NA, __IPHONE_3_2);

Answer 5

我只是把它扔到这里，但是如果你可以在某个地方使用SVG（比如在网页中，或者在使用某种SVG到核心图形库的应用程序中，我知道一些存在，但它不是理想的解决方案），我有代码：

<svg xmlns="http://www.w3.org/2000/svg" width="100%" height="100%" viewBox="0 0 1 1" preserveAspectRatio="none">
    <linearGradient id="g146" gradientUnits="userSpaceOnUse" x1="0%" y1="0%" x2="0%" y2="100%">
        <stop stop-color="#E2E5EA" offset="0" />
        <stop stop-color="#D1D3D9" offset="1" />
    </linearGradient>
    <rect x="0" y="0" width="1" height="1" fill="url(#g146)" />
</svg>

使用DigitalColor Meter应用程序创建（IMO是Apple应用程序的一个糟糕名称），Xcode4.5ß4和SVG Gradient Background Maker。

iPad分组tableView背景颜色？它是什么？

5 个答案: