ios - 如何从消息扩展创建 GIF 贴纸

Question

我构建了一个消息应用程序扩展，灵感来自 Ice Cream Builder(Apple 示例代码):https://developer.apple.com/library/content/samplecode/IceCreamBuilder/Introduction/Intro.html

我想使用动画 gif，而不是使用“png”图像作为我的贴纸。因为 gif 对于贴纸来说更有趣!

在示例代码中，贴纸是从 xcassets 文件夹中的文件 URL 创建的，PNG 格式。

func sticker(for mySticker: MySticker, completion: @escaping (_ sticker: MSSticker) -> Void) {

     // Determine the URL for the sticker.
    let fileName = mySticker.name! + ".png" 
    let url = cacheURL.appendingPathComponent(fileName)

    // Create an operation to process the request.
    let operation = BlockOperation {
        // Check if the sticker already exists at the URL.
        let fileManager = FileManager.default
        guard !fileManager.fileExists(atPath: url.absoluteString) else { return }

        // Create the sticker image and write it to disk.
        guard let image = UIImage(named:mySticker.name!), let imageData = UIImagePNGRepresentation(image) else { fatalError("Unable to build image for stickers") }

        do {
            try imageData.write(to: url, options: [.atomicWrite])
        } catch {
            fatalError("Failed to write sticker image to cache: \(error)")
        }
    }

    // Set the operation's completion block to call the request's completion handler.
    operation.completionBlock = {
        do {
            let sticker = try MSSticker(contentsOfFileURL: url, localizedDescription: "My Sticker")
            completion(sticker)
        } catch {
            print("Failed to write image to cache, error: \(error)")
        }
    }

    // Add the operation to the queue to start the work.
    queue.addOperation(operation)
}

我试图编辑文件名:

let fileName = mySticker.name! + ".gif" 

……当然不行

我注意到只有在 xcassets 文件夹中创建“贴纸包”时，动画 GIF 格式才能在 Xcode 中使用。

但是我的代码不能用它，这一行的错误:

 guard let image = UIImage(named:mySticker.name!), let imageData = UIImagePNGRepresentation(image) else { fatalError("Unable to build image for stickers") }

这似乎合乎逻辑，但我找不到解决方法。

Answer 1

解决方案非常简单。直接使用路径.gif。请注意，如果您的 gif 位于特定文件夹中，则此文件夹不能是文件夹引用。

func sticker(for mySticker: MySticker, completion: @escaping (_ sticker: MSSticker) -> Void) {

    let fileName = mySticker.name + ".gif"

    let url = cacheURL.appendingPathComponent(fileName)

    // Create an operation to process the request.
    let operation = BlockOperation {

    // Check if the sticker already exists at the URL.
     let fileManager = FileManager.default
     guard !fileManager.fileExists(atPath: url.absoluteString) else { return }

    // Create the sticker image and write it to disk.
    guard let image = UIImage(named:mySticker.name), let imageData = UIImagePNGRepresentation(image) else { fatalError("Unable to build image \(mySticker.name)") }

        do {
            try imageData.write(to: url, options: [.atomicWrite])

        } catch {
            fatalError("Failed to write sticker image \(mySticker.name) to cache: \(error)")
        }
    }


    // Set the operation's completion block to call the request's completion handler.
    operation.completionBlock = {
        do {
            let sticker = try MSSticker(contentsOfFileURL: url, localizedDescription: "My Sticker")
            completion(sticker)
        } catch {
            print("Failed to write image to cache, error: \(error)")
        }
    }
}

与

struct MySticker {
   var name: String
   var num: Int
}