ios - CGBitmapContextCreate 在 iOS 9 上停止工作

Question

所以这段代码曾经适用于 iOS 8，但不适用于 iOS 9

let bitsPerComponent = CGImageGetBitsPerComponent(cgImage)
let colorSpace = CGImageGetColorSpace(cgImage)
let bitmapInfo = CGImageGetBitmapInfo(cgImage)
let context =
    CGBitmapContextCreate(
        nil, newPixelWidth, newPixelHeight, bitsPerComponent, 0, colorSpace,
        bitmapInfo.rawValue)

CoreGraphics的解释是:

CGBitmapContextCreate: unsupported parameter combination:
    8 integer bits/component;
    32 bits/pixel;
    RGB color space model; kCGImageAlphaLast;
    2400 bytes/row.
Valid parameters for RGB color space model are:
    16  bits per pixel,      5  bits per component,      kCGImageAlphaNoneSkipFirst
    32  bits per pixel,      8  bits per component,      kCGImageAlphaNoneSkipFirst
    32  bits per pixel,      8  bits per component,      kCGImageAlphaNoneSkipLast
    32  bits per pixel,      8  bits per component,      kCGImageAlphaPremultipliedFirst
    32  bits per pixel,      8  bits per component,      kCGImageAlphaPremultipliedLast
    64  bits per pixel,      16 bits per component,      kCGImageAlphaPremultipliedLast
    64  bits per pixel,      16 bits per component,      kCGImageAlphaNoneSkipLast
    128 bits per pixel,      32 bits per component,      kCGImageAlphaNoneSkipLast |kCGBitmapFloatComponents
    128 bits per pixel,      32 bits per component,      kCGImageAlphaPremultipliedLast |kCGBitmapFloatComponents

但是 newPixelWidth 是 600 并且 600*4 = 2400。这是怎么回事？

Answer 1

我不是专家，但你没有给出自己的答案吗？

32  bits per pixel,      8  bits per component,      kCGImageAlphaNoneSkipFirst
32  bits per pixel,      8  bits per component,      kCGImageAlphaNoneSkipLast
32  bits per pixel,      8  bits per component,      kCGImageAlphaPremultipliedFirst
32  bits per pixel,      8  bits per component,      kCGImageAlphaPremultipliedLast

这些都不是kCGImageAlphaLast，所以我认为这就是问题所在。