iOS-快速创建未签名的字符

Question

我正在将一些Objective-C代码转换为Swift，并且其中包含以下代码：

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char rgba[4];
CGContextRef context = CGBitmapContextCreate(rgba, 1, 1, 8, 4, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);

CGContextDrawImage(context, CGRectMake(0, 0, 1, 1), image.CGImage);
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);


UIColor *averageColor = [UIColor colorWithRed:((CGFloat)rgba[0])/255.0 green:((CGFloat)rgba[1])/255.0 blue:((CGFloat)rgba[2])/255.0 alpha:alpha];
averageColor = [averageColor colorWithMinimumSaturation:0.15];

我已经设法轻松地转换了colorSpace，但是如何在Swift 3中创建未签名的字符？

我尝试了以下操作，但编译器未提示以下错误，它不起作用：

Cannot convert value of type '[CUnsignedChar]' to expected argument type 'UnsafeMutableRawPointer?'

这是代码：

 let colorSpace: CGColorSpace = CGColorSpaceCreateDeviceRGB()
 let rgba = [CUnsignedChar](repeating: 0,count: 4)
 // error on this line because of the rgba     
 let context: CGContext = CGContext.init(data: rgba, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: CGImageAlphaInfo.premultipliedLast | CGBitmapInfo.byteOrder32Big) 


context.draw(image.cgImage!, in: CGRect(x: 0, y: 0, width: 1, height: 1))

我再也走不了了

有人可以帮忙吗？

谢谢

Answer 1

尝试这个..

let colorSpace: CGColorSpace = CGColorSpaceCreateDeviceRGB()
let data = UnsafeMutableRawPointer.allocate(bytes: 4, alignedTo: 1) // 4 unsigned char = 4 bytes
let context: CGContext = CGContext.init(data: data, width: 1, height: 1, bitsPerComponent: 8, bytesPerRow: 4, space: colorSpace, bitmapInfo: CGImageAlphaInfo.premultipliedLast | CGBitmapInfo.byteOrder32Big)
let rgba = Array(UnsafeBufferPointer(start: data.assumingMemoryBound(to: UInt8.self), count: 4))
//  .... other