UserDefaults.standard.set(NSKeyedArchiver.archivedData(withRootObject: sortedImage), forKey: "StoredData.homePageImages")
需要10秒以上。这有意义吗?有什么建议吗?
func printTime() {
let date = Date()
let calendar = Calendar.current
let hour = calendar.component(.hour, from: date)
let minutes = calendar.component(.minute, from: date)
let seconds = calendar.component(.second, from: date)
print("HERE: hours = \(hour):\(minutes):\(seconds)")
}
let sortedImage = [UIImage]()
... append images to sortedImage (4 images)
printTime()
UserDefaults.standard.set(NSKeyedArchiver.archivedData(withRootObject: sortedImage), forKey: "StoredData.homePageImages")
printTime()
打印
HERE: hours = 4:54:11
HERE: hours = 4:54:23
对他人的建议:(还建议使用UIImageJPEGRepresentation并将其设置为0.5而不是UIImagePNGRepresentation,它可以压缩图像并缩短时间(约不到1秒)) < /强>
func saveImages(images: [UIImage]) -> [String] {
func saveImage(image: UIImage) -> String {
let imageData = NSData(data: UIImagePNGRepresentation(image)!)
let paths = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
let docs = paths[0] as NSString
let uuid = NSUUID().uuidString + ".png"
let fullPath = docs.appendingPathComponent(uuid)
_ = imageData.write(toFile: fullPath, atomically: true)
return uuid
}
var uuids = [String]()
for image in images {
uuids.append(saveImage(image: image))
}
print("saveImages:", uuids)
return uuids
}
func removeImages(uuids: [String]) {
func removeImage(uuid: String) {
let fileManager = FileManager.default
let nsDocumentDirectory = FileManager.SearchPathDirectory.documentDirectory
let nsUserDomainMask = FileManager.SearchPathDomainMask.userDomainMask
let paths = NSSearchPathForDirectoriesInDomains(nsDocumentDirectory, nsUserDomainMask, true)
guard let dirPath = paths.first else { return }
let filePath = "\(dirPath)/\(uuid)"
do {
try fileManager.removeItem(atPath: filePath)
} catch let error as NSError {
print(error.debugDescription)
}
}
for uuid in uuids {
removeImage(uuid: uuid)
}
print("removeImages:", uuids)
}
这个速度稍微快一点,大约5秒
printTime()
if let uuids = UserDefaults.standard.stringArray(forKey: "StoredData.homePageImage") {
removeImages(uuids: uuids)
}
let uuids = saveImages(images: sortedImage)
UserDefaults.standard.set(uuids, forKey: "StoredData.homePageImage")
printTime()
打印
HERE: hours = 5:59:38
removeImages: ["32231CF0-9194-4292-999F-71D7DC45D5DB.png", "39664081-0E81-458C-8E9E-2F3E907EAA2D.png", "B9EE3277-B170-43EC-B45A-EEE068B99D7B.png", "79E42843-8E67-49AA-AACC-50904D93011E.png"]
saveImages: ["C08EF14D-06D0-4456-842A-531FBC3B6678.png", "6666A3C3-949E-490E-97A9-19A5C942FB14.png", "623EFCF0-E38C-40FC-B7A5-32243D7914D0.png", "DA8DD110-5EF3-4CC4-99CA-455D8ECEFC62.png"]
HERE: hours = 5:59:43
这是get函数
func getImages(uuids: [String]) -> [UIImage] {
func getImage(uuid: String) -> UIImage? {
let nsDocumentDirectory = FileManager.SearchPathDirectory.documentDirectory
let nsUserDomainMask = FileManager.SearchPathDomainMask.userDomainMask
let paths = NSSearchPathForDirectoriesInDomains(nsDocumentDirectory, nsUserDomainMask, true)
if let dirPath = paths.first {
let imageURL = URL(fileURLWithPath: dirPath).appendingPathComponent(uuid)
return UIImage(contentsOfFile: imageURL.path)
}
return nil
}
var images = [UIImage]()
for uuid in uuids {
if let image = getImage(uuid: uuid) {
images.append(image)
}
}
return images
}
答案 0 :(得分:1)
当我在1MB JPEG上运行上面的代码时,我得到719个字节的数据,所以我认为它只是一个内存中的指针(在下次运行应用程序时无用)
我认为这不会为您提供可以存储在UserDefaults中的数据。我还建议只使用文件系统(Documents文件夹)来存储这些图像。