How to get MIME type for image or video in iOS 8 using PHAsset?

问题

I am using PHAsset in my application where I need to upload image and video to api, for that I need mime type of image and video. In previous version of iOS I was using following code but in iOS 8 I don't know how to get mimetype I have tried looking into apple PHAsset programming guide but unable to find it.

ALAssetRepresentation *representation = [asset defaultRepresentation];
NSString *mimeType = (__bridge_transfer NSString *)UTTypeCopyPreferredTagWithClass
        ((__bridge CFStringRef)[representation UTI], kUTTagClassMIMEType);

Looking for any guidance.

回答1:

PHContentEditingInput has property uniformTypeIdentifier. You can find more in the documentation.

@import MobileCoreServices.UTType;

...

PHAsset *asset = ...
PHContentEditingInputRequestOptions *options = ...
[asset requestContentEditingInputWithOptions:options completionHandler:^(PHContentEditingInput *contentEditingInput, NSDictionary *info) {
    NSString *MIME = (__bridge NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)contentEditingInput.uniformTypeIdentifier, kUTTagClassMIMEType);
}];

回答2:

Also you can find uniformTypeIdentifier from PHContentEditingInput class. For this; use requestContentEditingInput function from PHAsset

Don't forget to import MobileCoreServices

Sample Swift 3.1 code:

import MobileCoreServices


let options = PHContentEditingInputRequestOptions()
options.isNetworkAccessAllowed = true //for icloud backup assets

let asset : PHAsset = .....  //sampleAsset
asset.requestContentEditingInput(with: options) { (contentEditingInput, info) in
    if let uniformTypeIdentifier = contentEditingInput?.uniformTypeIdentifier {

        //check type here
        if uniformTypeIdentifier == (kUTTypeGIF as String) {
            debugPrint("This asset is a GIF👍")
        }

    }
}

回答3:

Use the requestImageDataForAsset method of PHImageManager. In it's resultBlock the method returns the UTI-Type for the asset.

回答4:

I ended up getting the MIME type for a PHAsset as follows (iOS 9+):

@implementation PHAsset (UTI)

- (NSString *)utiMimeType
{
    NSString *mimeType = @"image/jpeg";

    NSString *uType = [PHAssetResource assetResourcesForAsset:self].firstObject.uniformTypeIdentifier;
    if (uType) {
        NSString *tagMimeType = (__bridge NSString *)UTTypeCopyPreferredTagWithClass((__bridge CFStringRef)uType, kUTTagClassMIMEType);
        if (tagMimeType)
            mimeType = tagMimeType;
    }

    return mimeType;
}

@end

Couple things to call out/ways to improve:

I chose to default to image/jpeg if mimeType couldn't be derived.
It is assuming the first resource is the appropriate one. May not be the case for multi-resource assets (Live Photos, etc).
I haven't yet tested how/if it works as expected for assets in iCloud that need to be downloaded.

If anyone has insight on #2 or #3, it would be greatly appreciated. I'll update my answer when I find out more.

来源：https://stackoverflow.com/questions/28724615/how-to-get-mime-type-for-image-or-video-in-ios-8-using-phasset

标签

ios

ios8

mime-types

phasset