Detect permission of media library ios

问题:

In my app, I want to detect that if user give the permission to his media library or not. User may denied media library permission when system popup ask or later from setting. Is there any way to detect the status of media library permission?

Here is my code that access list of songs.

MPMediaQuery *everything = [MPMediaQuery songsQuery];
NSArray *songArray = [everything items];

Please see below screenshot where user can change Media Library permissions.

回答1:

-(void) checkMediaLibraryPermissions {
    [MPMediaLibrary requestAuthorization:^(MPMediaLibraryAuthorizationStatus status){
        switch (status) {
            case MPMediaLibraryAuthorizationStatusNotDetermined: {
                // not determined
                break;
            }
            case MPMediaLibraryAuthorizationStatusRestricted: {
                // restricted
                break;
            }
            case MPMediaLibraryAuthorizationStatusDenied: {
                // denied
                break;
            }
            case MPMediaLibraryAuthorizationStatusAuthorized: {
                // authorized
                break;
            }
            default: {
                break;
            }
        }
    }];
}

回答2:

Temporarily, i solved my problem by checking songArray object in below code

MPMediaQuery *everything = [MPMediaQuery songsQuery]; 
NSArray *songArray = [everything items];

If, user denied permission then songArray object is always nil, but if user allows permission to access to Media Library then songArray object have array of songs. Even if there will be no songs in device but user give permission to access Media Library then there will be array with 0 count.

回答3:

Swift 4 access check. The simple solution is as follows, and you can alter to include the other alternatives however in my case it was all access or nothing.

private func checkPermissionForMusic() -> Bool {
    switch MPMediaLibrary.authorizationStatus() {
    case .authorized:
        return true
    default:
        return false
    }
}

Caution about using the above solutions - they do perform as a block statement and do not return a value (return true or return "authorised") on the same thread; the result is handled on a background thread. If you decide to use the suggestions above, use a handler (call another function) to handle the result you're expecting. This solution on the other hand tells you immediately if you have access or not. No waiting required.

More info is available in the Apple Docs