将图像文件保存到临时目录答案

【问题标题】：Save image file to temp directory将图像文件保存到临时目录
【发布时间】：2016-03-03 01:15:34
【问题描述】：

我有一个名为“Image.png”的图像文件，它保存在我的主包中（就在项目导航器层次结构中的 ViewController.swift 文件旁边）。我想将此图像的副本保存到临时目录。我以前没做过，请问我可以使用什么代码？

【问题讨论】：

【解决方案1】：

这样的事情应该可以解决问题。我假设你想要 Swift 中的答案。

 /**
 * Copy a resource from the bundle to the temp directory.
 * Returns either NSURL of location in temp directory, or nil upon failure.
 *
 * Example: copyBundleResourceToTemporaryDirectory("kittens", "jpg")
 */
public func copyBundleResourceToTemporaryDirectory(resourceName: String, fileExtension: String) -> NSURL?
{
    // Get the file path in the bundle
    if let bundleURL = NSBundle.mainBundle().URLForResource(resourceName, withExtension: fileExtension) {

        let tempDirectoryURL = NSURL.fileURLWithPath(NSTemporaryDirectory(), isDirectory: true)

        // Create a destination URL.
        let targetURL = tempDirectoryURL.URLByAppendingPathComponent("\(resourceName).\(fileExtension)")

        // Copy the file.
        do {
            try NSFileManager.defaultManager().copyItemAtURL(bundleURL, toURL: targetURL)
            return targetURL
        } catch let error {
            NSLog("Unable to copy file: \(error)")
        }
    }

    return nil
}

虽然，我不太确定您为什么要这样做而不是直接访问捆绑资源。

【讨论】：

非常感谢，马特！
没问题@dimery2006，如果有帮助请考虑接受答案:)

【解决方案2】：

Swift 4.x 版本的 mszaro 的回答

/**
 * Copy a resource from the bundle to the temp directory.

 * Returns either NSURL of location in temp directory, or nil upon failure.
 *
 * Example: copyBundleResourceToTemporaryDirectory("kittens", "jpg")
 */
public func copyBundleResourceToTemporaryDirectory(resourceName: String, fileExtension: String) -> NSURL?
{
    // Get the file path in the bundle
    if let bundleURL = Bundle.main.url(forResource: resourceName, withExtension: fileExtension) {

        let tempDirectoryURL = NSURL.fileURL(withPath: NSTemporaryDirectory(), isDirectory: true)

        // Create a destination URL.
        let targetURL = tempDirectoryURL.appendingPathComponent("\(resourceName).\(fileExtension)")

        // Copy the file.
        do {
            try FileManager.default.copyItem(at: bundleURL, to: targetURL)
            return targetURL as NSURL
        } catch let error {
            NSLog("Unable to copy file: \(error)")
        }
    }

    return nil
}

【讨论】：

NSURL 不适用于 Swift 4。不要使用它。附加文件名和扩展名的正确语法是let targetURL = tempDirectoryURL.appendingPathComponent(resourceName).appendingPathExtension(fileExtension))

【解决方案3】：

这是 Swift 5

中的答案

/**
 * Copy a resource from the bundle to the temp directory.

 * Returns either URL of location in temp directory, or nil upon failure.
 *
 * Example: copyBundleResourceToTemporaryDirectory("kittens", "jpg")
 */

public func copyBundleResourceToTemporaryDirectory(resourceName: String, fileExtension: String) -> URL?
    {
        // Get the file path in the bundle
        if let bundleURL = Bundle.main.url(forResource: resourceName, withExtension: fileExtension) {

            let tempDirectoryURL = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)

            // Create a destination URL.
            let targetURL = tempDirectoryURL.appendingPathComponent(resourceName).appendingPathExtension(fileExtension)

            // Copy the file.
            do {
                try FileManager.default.copyItem(at: bundleURL, to: targetURL)
                return targetURL
            } catch let error {
                print("Unable to copy file: \(error)")
            }
        }

        return nil
    }

我建议阅读this article to learn more about temporary files

【讨论】：