Popping Sound

It sounds like there are two types of 'products' being sold - the actual physical goods and the premium listing (i.e.'seller can highlight' and 'premium account functionality'). Regarding the physical goods - you cannot use IAP and depending on how you interpret 11.2 you may, or may not, use a 'PayPal' like system within your app. You can use a PayPal like system accessed through your website for the physical goods. Regarding the premium listing - I think you must use IAP for that.

It's peculiar that a reinstall didn't fix that.First try correctly setting the catalog using the following command in Terminal (the whole thing, including the text that appears as a link):sudo softwareupdate --set-catalog https://swscan.apple.com/content/catalogs/others/index-10.11seed-10.11-10.10-10.9-mountainlion-lion-snowleopard-leopard.merged-1.sucatalog.gzAlso, have you tried booting into Safe Mode, or booting normally but creating a new temporary admin account and updating from there?Follow these steps to start up into safe mode.Start or restart your Mac.Immediately after you hear the startup sound, press and hold the Shift key.Release the Shift key when you see the Apple logo appear on the screen.After the Apple logo appears, it might take longer than usual to reach the login screen or your desktop. This is because your Mac performs a directory check of your startup disk as part of safe mode.If you're not sure if your Mac is started in safe mode, you can use System Information to check this. T

Sounds like a user-centric question for the public forums?

To use the MIDISynth AU, you need to include a SoundFont 2 (.sf2) or Downloadable Sounds (.dls) bank file with your app.When you first set up your AU, pass it the URL for the bank file using the kMusicDeviceProperty_SoundBankURL property. This is different that what the Sampler AU does with samples -- here, you are passing it the specific path using [NSBundle bundleForClass: pathForResource:].The MIDISynth loads instrument presets out of the bank you specify in response to program change messages in your MIDI file. If you use the MIDISynth in conjunction with the MusicPlayer/Sequence API, it will take care of the extra step you will need to pre-load all the instruments during the preroll stage, before you start playing.If you goal is straightforward MIDI file playback, I *strongly* recommend the new AVMIDIPlayer which is part of the AVFoundation audio API. This lets you get away from the older C-based APIs completely.The other possibility, if you need more flexibility, is the new iOS 9 AVAud

Maybe a DRM thing? If you could get the URL, you could presumably open it with an AVAssetReader and start reading samples.IIRC, the same thing happens with any .m4p (FairPlay audio, from the pre-iTunes-Plus era) that you try to access via the Media Player API.—Chris

Thanks for clearing that up!I'd also just like to mention, it doesn't seem we can use the NSDownloadsDirectory either, as trying to create the directory returns an error (The operation couldn’t be completed. Operation not permitted). So it would appear that the only options on iOS are loading from the bundle or from the Documents directory. Not ideal when you also want to enable iTunes File Sharing for other content.That being said, I did think of a workaround: put the content in an arbitrary location, and when loading the .aupreset file, rewrite all the file references to refer to that location before setting it on the Audio Unit. For now I'm just going to use the documents directory but if I ever need to enable iTunes File Sharing I may have to resort to the workaround.

It could be that you've unintentionally instructed Xcode to treat your file as plaintext. Open your file in the main editor and open the File Inspector. Right below the file name is a pop-up button labeled Type. Make sure that's set to Objective-C Source. If that doesn't work, try quitting and relaunching Xcode. That will reset the indexing and code completion subsystems.