判断用户是否禁止该App使用设备麦克风

#import <AVFoundation/AVAudioSession.h>

...
if ([[ AVAudioSession sharedInstance ] respondsToSelector : @selector (requestRecordPermission:)]) {
    [[ AVAudioSession sharedInstance ] performSelector : @selector (requestRecordPermission:) withObject :^( BOOL granted) {
        if (granted) {
            // Microphone enabled code
            NSLog( @"Microphone is enabled.." );
        }
        else {
            // Microphone disabled code
            NSLog( @"Microphone is disabled.." );

            // We're in a background thread here, so jump to main thread to do UI work.
            dispatch_async(dispatch_get_main_queue(), ^{
                [[[[ UIAlertView alloc ] initWithTitle : @"Microphone Access Denied"
                                       message : @"This app requires access to your device's Microphone.\n\nPlease enable Microphone access for this app in Settings / Privacy / Microphone"
                                      delegate :nil
                             cancelButtonTitle : @"Dismiss"
                             otherButtonTitles :nil ] autorelease ] show ];
            });
        }
    }];
}