如何确定cameraDevice是否可用？

Question

在我目前的应用程序中,我允许用户在线提交图像到图像服务.我允许用户从相册中选择或使用相机拍照.

但是,我有一个问题.如果正在使用的设备没有摄像头且用户选择拍照,则应用程序崩溃.我需要能够确定设备是否具有使用cameraDevice的能力.

下面是我目前提供UIActionSheet的代码,它允许用户选择不同的选项.

#pragma mark -
#pragma mark UIImagePickerController
- (IBAction)ImagePicker {
UIActionSheet *sheet = [[UIActionSheet alloc] 
                        initWithTitle:@"" delegate:self 
                        cancelButtonTitle:@"Cancel" 
                        destructiveButtonTitle:nil 
                        otherButtonTitles:@"Choose An Existing Photo", @"Take A Photo", nil];
sheet.actionSheetStyle = UIActionSheetStyleDefault;
[sheet showInView:self.view];
[sheet release];
}

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {

if (buttonIndex == 0) {
    //Okay the UIImagePickerControllerSourceTypeSavedPhotosAlbum displays the 
    NSLog(@"Album");
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
    [self presentModalViewController:picker animated:YES];
    [picker release];

} else if (buttonIndex == 1) {
    NSLog(@"Camera");
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
    picker.delegate = self;
    picker.sourceType = UIImagePickerControllerSourceTypeCamera;
    [self presentModalViewController:picker animated:YES];
    [picker release];
}
}

提前致谢!

Answer 1

if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) { NSLog(@"No camera!"); }