iOS 权限判断（相机，相册，定位，录音）

相机权限
NSString *mediaType = AVMediaTypeVideo;
AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:mediaType];
if(authStatus == ALAuthorizationStatusRestricted || authStatus == ALAuthorizationStatusDenied){
 //无权限
 NSString *tips = [NSString stringWithFormat:@"请在iPhone的”设置-隐私-相机“选项中，允许%@访问你的手机相机",NSLocalizedString(@"AppName",@"GMChatDemo")];
 [UIAlertView showWithTitle:@" " message:tips cancelButtonTitle:@"好" otherButtonTitles:nil tapBlock:nil];
 return;
 }

相册权限
 ALAuthorizationStatus author = [ALAssetsLibrary authorizationStatus];
 if (author == kCLAuthorizationStatusRestricted || author ==kCLAuthorizationStatusDenied){
 //无权限
  NSString *tips = [NSString stringWithFormat:@"请在iPhone的”设置-隐私-照片“选项中，允许%@访问你的照片",NSLocalizedString(@"AppName",@"GMChatDemo")];
   [UIAlertView showWithTitle:@" " message:tips cancelButtonTitle:@"好" otherButtonTitles:nil tapBlock:nil];
                return;
 }

麦克风权限（录音等）
+ (BOOL)canRecord
{
    __block BOOL bCanRecord = YES;
    if ([[[UIDevice currentDevice] systemVersion] compare:@"7.0"] != NSOrderedAscending)
    {
        AVAudioSession *audioSession = [AVAudioSession sharedInstance];
        if ([audioSession respondsToSelector:@selector(requestRecordPermission:)]) {
            [audioSession performSelector:@selector(requestRecordPermission:) withObject:^(BOOL granted) {
                bCanRecord = granted;
            }];
        }
    }
    return bCanRecord;
}

定位权限
CLAuthorizationStatus status = [CLLocationManager authorizationStatus];
 if (kCLAuthorizationStatusDenied == status || kCLAuthorizationStatusRestricted == status) {
  [self showHint:NSLocalizedString(@"location.open","please open location")];
  return;
    }