如何在Swift中的路径中找到文件UTI for file，withouth pathExtension [英] How to find file UTI for file, withouth pathExtension, in a path in Swift

问题描述

我一直试图将此代码转换为示例（在Objective-c中）没有运气。

I've been trying to convert this code which I had from this example (in Objective-c) with no luck.

    String *path; // contains the file path

    // Get the UTI from the file's extension:

    CFStringRef pathExtension = (__bridge_retained CFStringRef)[path pathExtension];
    CFStringRef type = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension, NULL);
    CFRelease(pathExtension);

    // The UTI can be converted to a mime type:

    NSString *mimeType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass(type, kUTTagClassMIMEType);
    if (type != NULL)
        CFRelease(type);

我的代码是这个

    import MobileCoreServices
    let path: String?
    let pathExt = path.pathExtension as CFStringRef
    let type = UTTypeCreatePreferredIdentifierForTag(kUTTagClassFilenameExtension, pathExtension, NULL);
    let mimeType = UTTypeCopyPreferredTagWithClass(type, kUTTagClassMIMEType)
    if type != Null
            CFRelease(type)

我想要做的就是找出文件是图像还是视频文件

All I want to do is find out if a file is an image or a video file

推荐答案

您可以使用 URL 方法 resourceValues（forKeys :) 来获取文件 URL TypeIdentifierKey 返回文件统一类型标识符（UTI）。您只需要检查返回的值是视频的com.apple.m4v-video，图像的public.jpeg或public.png等等。您可以向URL添加typeIdentifier属性扩展以返回TypeIdentifierKey字符串值，如下所示：

You can use URL method resourceValues(forKeys:) to get the file URL TypeIdentifierKey which returns the file uniform type identifier (UTI). You just need to check if the returned value is "com.apple.m4v-video" for videos, "public.jpeg" or "public.png" for images and so on. You can add a typeIdentifier property extension to URL to return the TypeIdentifierKey string value as follow:

Xcode 9•Swift 4 或 Xcode 8.3.2•Swift 3.1

extension URL {
    var typeIdentifier: String? {
        return (try? resourceValues(forKeys: [.typeIdentifierKey]))?.typeIdentifier
    }
    var localizedName: String? {
        return (try? resourceValues(forKeys: [.localizedNameKey]))?.localizedName
    }
}

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