使用照片框架按图片大小过滤照片库

Question

我正在构建iOS应用程序，用于从用户的照片库中选择屏幕截图。该应用程序工作，除了我可以显示所有照片，我只需要屏幕截图。为了检测屏幕截图，我想将图像大小与屏幕大小相匹配。

var userScreenshots: PHFetchResult!
let screenWidth = view.bounds.size.width * 2
let screenHeight = view.bounds.size.height * 2
let options = PHFetchOptions()
// Following line needs to be changed —>
options.predicate = NSPredicate(format: "(pixelWidth & %d) != 0 || (pixelHeight & %d) != 0", screenWidth, screenHeight)
options.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]
userScreenshots = PHAsset.fetchAssetsWithOptions(options)

崩溃：

2015-06-22 23:00:24.540 Altershot[95046:24515142] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unsupported predicate in fetch options: pixelWidth & 0 != 0'

请解释如何正确定义这个谓词。

Answer 1

这是正确的代码。注意，这不是幻数2，而是scale的通用属性，因为iPhone 6 Plus的规模为3。我还附上了风景截图，谢谢你的评论。此外，屏幕大小公式也进行了改进，为iOS 9多任务处理做好了准备。

var userScreenshots: PHFetchResult!
let scale = UIScreen.mainScreen().scale
let screenWidth = UIScreen.mainScreen().bounds.width * scale
let screenHeight = UIScreen.mainScreen().bounds.height  * scale
let options = PHFetchOptions()
options.predicate = NSPredicate(format: "(pixelHeight == %d AND pixelWidth == %d) OR (pixelHeight == %d AND pixelWidth == %d)", argumentArray: [screenHeight, screenWidth, screenWidth, screenHeight])
options.sortDescriptors = [NSSortDescriptor(key: "creationDate", ascending: true)]
userScreenshots = PHAsset.fetchAssetsWithOptions(options)