Changing iphone lock screen programmatically when app is running in background

问题

I am developing an iphone app where i have to change lockscreen image programmatically when app is running in background.I have got lots of stuff saying it is not possible but there is an app for this please let me know how to acheive this.

Thanks.

回答1:

The only way you can change the lockscreen image is when you are playing audio. Police Scanner+ does play audio, and therefore can set an image. This only works with iOS 5+ and is done something like this.

- (void)setupNowPlayingInfoCenter:(MPMediaItem *)currentSong
{
    NSString *ver = [[UIDevice currentDevice] systemVersion];
    CGFloat version = 4.0;
    if ([ver length] >= 3)
    {
        version = [[ver substringToIndex:3] floatValue];
    }

    if (version >= 5.0)
    {
        MPMediaItemArtwork *artwork = [currentSong valueForProperty:MPMediaItemPropertyArtwork];

        MPNowPlayingInfoCenter *infoCenter = [MPNowPlayingInfoCenter defaultCenter];

        if (currentSong == nil)
        {
            infoCenter.nowPlayingInfo = nil;
            return;
        }

        infoCenter.nowPlayingInfo = [NSDictionary dictionaryWithObjectsAndKeys:
                [currentSong valueForKey:MPMediaItemPropertyTitle], MPMediaItemPropertyTitle,
                [currentSong valueForKey:MPMediaItemPropertyArtist], MPMediaItemPropertyArtist,
                [currentSong valueForKey:MPMediaItemPropertyAlbumTitle], MPMediaItemPropertyAlbumTitle,
                [currentSong valueForKey:MPMediaItemPropertyAlbumTrackCount], MPMediaItemPropertyAlbumTrackCount,
                [currentSong valueForKey:MPMediaItemPropertyAlbumTrackNumber], MPMediaItemPropertyAlbumTrackNumber,
                artwork, MPMediaItemPropertyArtwork,
                [currentSong valueForKey:MPMediaItemPropertyComposer], MPMediaItemPropertyComposer,
                [currentSong valueForKey:MPMediaItemPropertyDiscCount], MPMediaItemPropertyDiscCount,
                [currentSong valueForKey:MPMediaItemPropertyDiscNumber], MPMediaItemPropertyDiscNumber,
                [currentSong valueForKey:MPMediaItemPropertyGenre], MPMediaItemPropertyGenre,
                [currentSong valueForKey:MPMediaItemPropertyPersistentID], MPMediaItemPropertyPersistentID,
                [currentSong valueForKey:MPMediaItemPropertyPlaybackDuration], MPMediaItemPropertyPlaybackDuration,
                [NSNumber numberWithInt:self.mediaCollection.nowPlayingIndex + 1], MPNowPlayingInfoPropertyPlaybackQueueIndex,
                [NSNumber numberWithInt:[self.mediaCollection count]], MPNowPlayingInfoPropertyPlaybackQueueCount, nil];
    }
}

回答2:

there is No way to do this effect unless a app runs in a jailbreak iDevice ( and it means the app can't be submitted to App Store).

来源：https://stackoverflow.com/questions/12835380/changing-iphone-lock-screen-programmatically-when-app-is-running-in-background