如何检查文件是否存在于 Swift 的 Documents 目录中? [英] How to check if a file exists in the Documents directory in Swift?

问题描述

如何在Swift中检查Documents目录下是否存在文件?

How to check if a file exists in the Documents directory in Swift?

我正在使用 [ .writeFilePath ] 方法将图像保存到 Documents 目录中，我想在每次启动应用程序时加载它.但是如果没有保存的图像，我有一个默认图像.

I am using [ .writeFilePath ] method to save an image into the Documents directory and I want to load it every time the app is launched. But I have a default image if there is no saved image.

但我无法理解如何使用 [ func fileExistsAtPath(_:) ] 函数.有人可以举一个使用传递路径参数的函数的例子.

But I just cant get my head around how to use the [ func fileExistsAtPath(_:) ] function. Could someone give an example of using the function with a path argument passed into it.

我相信我不需要在那里粘贴任何代码，因为这是一个通用问题.任何帮助将不胜感激.

I believe I don't need to paste any code in there as this is a generic question. Any help will be much appreciated.

干杯

推荐答案

Swift 4.x 版本

    let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
    let url = NSURL(fileURLWithPath: path)
    if let pathComponent = url.appendingPathComponent("nameOfFileHere") {
        let filePath = pathComponent.path
        let fileManager = FileManager.default
        if fileManager.fileExists(atPath: filePath) {
            print("FILE AVAILABLE")
        } else {
            print("FILE NOT AVAILABLE")
        }
    } else {
        print("FILE PATH NOT AVAILABLE")
    }

Swift 3.x 版本

    let path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
    let url = URL(fileURLWithPath: path)

    let filePath = url.appendingPathComponent("nameOfFileHere").path
    let fileManager = FileManager.default
    if fileManager.fileExists(atPath: filePath) {
        print("FILE AVAILABLE")
    } else {
        print("FILE NOT AVAILABLE")
    }

Swift 2.x 版本，需要使用URLByAppendingPathComponent

    let path = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as String
    let url = NSURL(fileURLWithPath: path)
    let filePath = url.URLByAppendingPathComponent("nameOfFileHere").path!
    let fileManager = NSFileManager.defaultManager()
    if fileManager.fileExistsAtPath(filePath) {
        print("FILE AVAILABLE")
    } else {
        print("FILE NOT AVAILABLE")
    }

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