loadImageFromDisk--函数修改 swift

Question

im使用下面的代码从磁盘上加载下载的图像，当文件存在时，我可以加载它作为图像。如果它不存在，图像返回为nil。

我怎样才能修改代码，用从我的asset文件夹中加载一个名为default.png的占位图来代替返回nil。因此，不是返回nil，而是总是有一个图像返回，要么是下载的一个试图加载，或者如果它不存在，我自己的资产图像。

func loadImageFromDiskWith(fileName: String) -> UIImage? {
  let documentDirectory = FileManager.SearchPathDirectory.documentDirectory

    let userDomainMask = FileManager.SearchPathDomainMask.userDomainMask
    let paths = NSSearchPathForDirectoriesInDomains(documentDirectory, userDomainMask, true)

    if let dirPath = paths.first {
        let imageUrl = URL(fileURLWithPath: dirPath).appendingPathComponent(fileName)
        let image = UIImage(contentsOfFile: imageUrl.path)
        return image
    }
    return nil
}

Answer 1

你可以做如下 -

func loadImageFromDiskWith(fileName: String) -> UIImage {
  let documentDirectory = FileManager.SearchPathDirectory.documentDirectory

    let userDomainMask = FileManager.SearchPathDomainMask.userDomainMask
    let paths = NSSearchPathForDirectoriesInDomains(documentDirectory, userDomainMask, true)
    var image = UIImage(named: "default") // Make sure there must be "default.png" in your main bundle.
    if let dirPath = paths.first {
        let imageUrl = URL(fileURLWithPath: dirPath).appendingPathComponent(fileName)
        if FileManager.default.fileExists(atPath: imageUrl.path) { //Check here for file existence. It won't crash.
              image = UIImage(contentsOfFile: imageUrl.path)
         }
    }

    return image
}