swift - 如何检查在 swift 中声明的类型为 UnsafeMutablePointer 的变量的值？

Question

这个问题已经有答案了:

NSFileManager fileExistsAtPath:isDirectory and swift (5 个回答)

已关闭 4 年前。

我需要检查 Swift 中类型为 UnsafeMutablePointer? 的函数返回的变量的值。

声明如下:

    var isDirectory: UnsafeMutablePointer<ObjCBool>?

当我打印出来时:

    print(isDirectory)

我得到:

nil

我不太擅长将 Swift 与 Objective-C 混合。任何帮助将不胜感激。

这是我实际的完整代码:

    let directoryURL: URL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false)

    let pathOldLocalStorage: String = directoryURL.path + "/OldLocalStorage"

    FileManager.default.createFile(atPath: pathOldLocalStorage, contents: nil, attributes: nil)

    var isDirectory: UnsafeMutablePointer<ObjCBool>?

    let fileExists: Bool = FileManager.default.fileExists(atPath: pathOldLocalStorage, isDirectory: isDirectory)

    print("fileExists=", fileExists, "isDirectory=", isDirectory as Any)

这是调试窗口结果:

fileExists= true isDirectory= nil

Answer 1

你需要这样调用它:

var isDirectory: ObjCBool = false

let fileExists: Bool = FileManager.default.fileExists(atPath: pathOldLocalStorage, isDirectory: &isDirectory)

if fileExists {
    print("isDirectory=\(isDirectory)")
}