针对 URL 扩展的 iOS15 UTType 弃用

Question

使用Swift5.5、iOS15.0.1，

从 iOS15 开始，我意识到与我现有的 URL 扩展相关的一些弃用行为正在发生。

我没有找到任何关于如何重写现有扩展的好的文档。

这是我目前的实现，大约。 16条折旧警告，我不知道如何使用iOS15规避。对此的任何想法都非常感谢！

extension URL {
    func mimeType() -> String {
        let pathExtension = self.pathExtension
        if let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension as NSString, nil)?.takeRetainedValue() {
            if let mimetype = UTTypeCopyPreferredTagWithClass(uti, kUTTagClassMIMEType)?.takeRetainedValue() {
                return mimetype as String
            }
        }
        return "application/octet-stream"
    }
    
    var containsImage: Bool {
        let mimeType = self.mimeType()
        guard let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
            return false
        }
        return UTTypeConformsTo(uti, kUTTypeImage)
    }
    
    var containsAudio: Bool {
        let mimeType = self.mimeType()
        guard let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
            return false
        }
        return UTTypeConformsTo(uti, kUTTypeAudio)
    }
    
    var containsVideo: Bool {
        let mimeType = self.mimeType()
        guard  let uti = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, mimeType as CFString, nil)?.takeRetainedValue() else {
            return false
        }
        return UTTypeConformsTo(uti, kUTTypeMovie)
    }
}

Answer 1

所有的 kUTType... 常量和全局 C 函数都被 UTType 结构取代。 https://developer.apple.com/documentation/uniformtypeidentifiers/uttype

只需import UniformTypeIdentifiers 就可以了。

这是一个将文件扩展名转换为 mime 类型的简单示例：

let ext = "txt"
if let type = UTType(filenameExtension: ext) {
// or: if let type = UTType(tag: ext, tagClass: .filenameExtension, conformingTo:nil) {
    if let mime = type.preferredMIMEType {
        print(mime) // "text/plain"
    }
}

Answer 2

我的初始 URL 扩展的 iOS15 兼容重写如下所示：

import UniformTypeIdentifiers

extension URL {
    func mimeType() -> String {
        let pathExtension = self.pathExtension
        if let type = UTType(filenameExtension: pathExtension) {
            if let mimetype = type.preferredMIMEType {
                return mimetype as String
            }
        }
        return "application/octet-stream"
    }
    
    var containsImage: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .image)
        }
        return false
    }
    
    var containsAudio: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .audio)
        }
        return false
    }
    
    var containsMovie: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .movie)   // ex. .mp4-movies
        }
        return false
    }
    
    var containsVideo: Bool {
        let mimeType = self.mimeType()
        if let type = UTType(mimeType: mimeType) {
            return type.conforms(to: .video)
        }
        return false
    }
}

Answer 3

为了兼容 iOS 15 及更早版本获取正确的 UUType，因为 kUTType 已被弃用，您可以使用此代码

var UTTypeID : Array = [ "url", "data", "plainText"]

 // iOS 15 Deprecated kUTType, use UTType
func UTTypeCompat(strID : String) -> String
{
    //0 - URL, 1 - Data, 2 - PlainText
    let indexUTType:Int? = UTTypeID.firstIndex(of: strID)
    
    if #available(iOS 15.0, *)
    {
        switch indexUTType {
        case 0:
            return UTType.url.identifier
        case 1:
            return UTType.data.identifier
        case 2:
            return UTType.plainText.identifier
        default:
            NSLog("Unsupported UUtype: \(strID)")
            break
        }
    }
    else
    {
        switch indexUTType {
        case 0:
            return kUTTypeURL as String
        case 1:
            return kUTTypeData as String
        case 2:
            return kUTTypePlainText as String
        default:
            NSLog("Unsupported UUtype: \(strID)")
            break
        }
    }
    // throw Exception
    return "Err"
}

以及如何获取任何 iOS 版本的标识符

    NSLog(UTTypeCompat(strID: "url"))
    NSLog(UTTypeCompat(strID: "data"))
    NSLog(UTTypeCompat(strID: "plainText"))