CGBitmapContextCreate停止为iOS 9工作

Question

因此，这段代码用于iOS 8，但停止了对iOS 9的工作。

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和600*4 = 2400。这里怎么回事？

Answer 1

我不是专家，但你没有给出你自己的答案吗？

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

所有这些都不是kCGImageAlphaLast，所以我认为这就是问题所在。