保存图像然后加载到Swift（iOS） [英] Saving image and then loading it in Swift (iOS)

问题描述

我使用saveImage保存图像。

I am saving an image using saveImage.

func saveImage (image: UIImage, path: String ) -> Bool{

    let pngImageData = UIImagePNGRepresentation(image)
    //let jpgImageData = UIImageJPEGRepresentation(image, 1.0)   // if you want to save as JPEG

    print("!!!saving image at:  \(path)")

    let result = pngImageData!.writeToFile(path, atomically: true)

    return result
}

新信息：

保存文件无法正常工作（打印[ - ] ERROR SAVING FILE） -

New info:

Saving file does not work properly ("[-] ERROR SAVING FILE" is printed)--

            // save your image here into Document Directory
        let res = saveImage(tempImage, path: fileInDocumentsDirectory("abc.png"))
        if(res == true){
            print ("[+] FILE SAVED")
        }else{
            print ("[-] ERROR SAVING FILE")
        }

为什么saveImage函数没有保存图像？访问权？

Why doesn't the saveImage function save the image? Access rights?

调试信息说：

!!!saving image at:  file:///var/mobile/Applications/BDB992FB-E378-4719-B7B7-E9A364EEE54B/Documents/tempImage

然后我使用

fileInDocumentsDirectory("tempImage")

结果是正确的。

然后我使用此路径加载文件

Then I am loading the file using this path

    let image = UIImage(contentsOfFile: path)

    if image == nil {

        print("missing image at: \(path)")
    }else{
        print("!!!IMAGE FOUND at: \(path)")
    }

路径正确，但消息是在...处丢失图像。文件是否以某种方式无法访问或未存储？这种行为可能是什么原因？

The path is correct, but the message is "missing image at..". Is the file somehow inaccessible or not stored? What can be a reason for this behavior?

我正在使用ios 7和带有ios 7模拟器的iphone 5在iphone 4上测试此代码。

I am testing this code on iphone 4 with ios 7 and iphone 5 with ios 7 simulator.

编辑：
1. fileInDocumentsDirectory函数

1. The fileInDocumentsDirectory function

func fileInDocumentsDirectory(filename: String) -> String {

    let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
    let fileURL = documentsURL.URLByAppendingPathComponent(filename).absoluteString
    return fileURL        
}

推荐答案

Swift 3

此功能会将图像保存在文档文件夹中：

This function will save an image in the documents folder:

func saveImage(image: UIImage) -> Bool {
    guard let data = UIImageJPEGRepresentation(image, 1) ?? UIImagePNGRepresentation(image) else {
        return false
    }
    guard let directory = try? FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false) as NSURL else {
        return false
    }
    do {
        try data.write(to: directory.appendingPathComponent("fileName.png")!)
        return true
    } catch {   
        print(error.localizedDescription)
        return false
    }
}

使用：

let success = saveImage(image: UIImage(named: "image.png")!)

---

此功能将获得该图像：

---

This function will get that image:

func getSavedImage(named: String) -> UIImage? {
    if let dir = try? FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false) {
        return UIImage(contentsOfFile: URL(fileURLWithPath: dir.absoluteString).appendingPathComponent(named).path)
    }
    return nil
}

使用：

if let image = getSavedImage(named: "fileName") {
    // do something with image
}

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