在没有子分类的情况下使UIView成为渐变的背景 [英] Make Background of UIView a Gradient Without Sub Classing

问题描述

有没有办法让UIView的背景成为渐变而不进行子类化？我宁愿不使用图像文件来实现这一点。只是为了为背景画一个渐变来创建UIView似乎很愚蠢。

Is there a way to make the background of a UIView a gradient without subclassing it? I'd rather not use an image file to accomplish this either. It just seems obtuse to have to subclass UIView just to draw a gradient for the background.

推荐答案

你可以使用 + [UIColor colorWithPatternImage：] 生成带图案的背景。示例（带上自己的CGGradient）：

You can use +[UIColor colorWithPatternImage:] to produce a patterned background. Example (bring your own CGGradient):

// Allocate color space
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// Allocate bitmap context
CGContextRef bitmapContext = CGBitmapContextCreate(NULL, 320, 480, 8, 4 * 320, colorSpace, kCGImageAlphaNoneSkipFirst);
//allocate myGradient
CGFloat locationList[]  = {0.0f, 1.0f};
CGFloat colorList[]     = {0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 0.0f, 0.0f};
CGGradientRef myGradient   = CGGradientCreateWithColorComponents(colorSpace, colorList, locationList, 2);
// Draw Gradient Here
CGContextDrawLinearGradient(bitmapContext, myGradient, CGPointMake(0.0f, 0.0f), CGPointMake(320.0f, 480.0f), 0);
// Create a CGImage from context
CGImageRef cgImage = CGBitmapContextCreateImage(bitmapContext);
// Create a UIImage from CGImage
UIImage *uiImage = [UIImage imageWithCGImage:cgImage];
// Release the CGImage
CGImageRelease(cgImage);
// Release the bitmap context
CGContextRelease(bitmapContext);
// Release the color space
CGColorSpaceRelease(colorSpace);
// Create the patterned UIColor and set as background color
[targetView setBackgroundColor:[UIColor colorWithPatternImage:image]];

创建 UIView 虽然是子类。它也将使用更少的内存。

It will probably be simpler to just create a UIView subclass though. It will use less memory as well.

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