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，但我可以显示所有照片，我只需要截图。要检测屏幕截图，我想将图像大小与屏幕大小匹配。

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此谓词。

Answer 1

这是正确的代码。请注意，由于iPhone 6 Plus的比例为2，因此scale通用属性具有幻数3。我还包括了横向截图，感谢您的评论。此外，屏幕尺寸公式得到了改进，为iOS 9多任务处理做好准备。

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)

使用照片框架按照图片大小过滤照片库

1 个答案: