ios passing a void* into UISaveVideoAtPathToSavedPhotosAlbum in Swift

问题

I'm new to Swift. I'm trying to use the method signature in my class:

func UISaveVideoAtPathToSavedPhotosAlbum(_ videoPath: String!,
                                   _ completionTarget: AnyObject!,
                                   _ completionSelector: Selector,
                                   _ contextInfo: CMutableVoidPointer)

The last argument, contextInfo, is a void * in obj-c.

I get an NSDictionary not a subtype of CMutableVoidPointer error if I pass a dictionary in Swift. Would appreciate any help with this. I don't know how to pass a void * equivalent argument in Swift without getting that error.

回答1:

Objective C - Void*

Swift - UnsafeMutablePointer

.. Example

// Your call to save video to camera roll

UISaveVideoAtPathToSavedPhotosAlbum(yourVideoPath, self, "video:didFinishSavingWithError:contextInfo:", nil)

// Your Completion Handler after video is saved

    func video(videoPath: String, didFinishSavingWithError error: NSError, contextInfo info: UnsafeMutablePointer<Void>) {
// your completion code handled here

}

回答2:

// Use `var`, not `let`
var userInfo: NSDictionary = ....
UISaveVideoAtPathToSavedPhotosAlbum(..., ..., ..., &userInfo)

CMutableVoidPointer is void *
CConstVoidPointer is const void *

回答3:

Swift 4.2

You can pass a NSDictionary as an UnsafeMutablePointer following a few steps:

1) declare a dictionary as a property of your view controller

var userInfo: NSDictionary = [:]

2) Second you will need to declare a method to be called when your picker is finished saving your image/video asynchronously:

@objc func image(_ image: UIImage, didFinishSavingWithError error: Error?, contextInfo: UnsafeRawPointer) {
    print(#function)
    let infoDict = Unmanaged<NSDictionary>
            .fromOpaque(contextInfo)
            .takeUnretainedValue()
        as? [String: Any] ?? [:]
    print("infoDict", infoDict )
}

3) You will need to convert your NSDictionary to a UnsafeMutableRawPointer:

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
    print(#function)
    if let img = info[.originalImage] as? UIImage {
        userInfo = info as NSDictionary
        UIImageWriteToSavedPhotosAlbum(img,
                                       self,
                                       #selector(image),
                                       UnsafeMutableRawPointer(
                                            Unmanaged
                                            .passUnretained(userInfo)
                                            .toOpaque()))
    }
    dismiss(animated: true)
}

来源：https://stackoverflow.com/questions/24471744/ios-passing-a-void-into-uisavevideoatpathtosavedphotosalbum-in-swift

标签

ios

objective-c

swift

void-pointers