ios - 使用CGImageMetadataSetTagWithPath设置exif的用户评论字段的路径是什么？

Question

使用CGImageMetadataSetTagWithPath设置exif的用户评论字段的路径是什么？

https://developer.apple.com/documentation/imageio/1465409-cgimagemetadatasettagwithpath

Answer 1

它适用于exif:UserComment:

guard let tag = CGImageMetadataTagCreate(
    kCGImageMetadataNamespaceExif,
    kCGImageMetadataPrefixExif,
    kCGImagePropertyExifUserComment,
    .string,
    "my exif comment" as CFString) else { fatalError("Metadata tag not created") }

let metadata = CGImageMetadataCreateMutable()

CGImageMetadataSetTagWithPath(
    metadata,
    nil,
    "exif:UserComment" as CFString,
    tag)

---

编辑

在撰写本文时，如果需要 ImageIO 函数的文档，应该按住 Cmd 键并单击这些函数中的每一个。它的格式似乎没有更新，因此没有显示在 Xcode 或其网络界面 (developer.apple.com) 中。

我们在 CGImageMetadataCopyTagWithPath 函数的文档中有更多关于如何形成路径的信息。摘录:

A string representing a path to the desired tag. Paths consist of a tag prefix (i.e. "exif") joined with a tag name (i.e. "Flash") by a colon (":"), such as CFSTR("exif:Flash").

我们可以使用以下代码代替硬编码值:

let path = "\(kCGImageMetadataPrefixExif):\(kCGImagePropertyExifUserComment)" as CFString