# Use virtual backgrounds

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> The code on this page only works with the **custom UI**.

Use `isSupportVirtualBG` in `MobileRTCMeetingService` to determine whether the device supports virtual backgrounds, then use `MobileRTCMeetingService` to enable them. You can also check to see if the smart virtual background - virtual backgrounds with green screens - are supported.

```swift
if let meetingService = MobileRTC.shared().getMeetingService(), meetingService.isSupportVirtualBG() {
    // Virtual background is supported

    // Check if smart virtual background is supported
    meetingService.isDeviceSupportSmartVirtualBG()
}
```

```objectivec
MobileRTCMeetingService *meetingService = [[MobileRTC sharedRTC] getMeetingService];
if (meetingService != nil && [meetingService isSupportVirtualBG]) {
    [meetingService isDeviceSupportSmartVirtualBG];
}
```

If the device supports virtual backgrounds, use `meetingService` to list, add, remove, and set virtual backgrounds.

```swift
// To list available virtual background
if let listOfVirtualBG:[MobileRTCVirtualBGImageInfo] = meetingService.getBGImageList() {
    // This list will contained a NONE, BLUR or Item (self added) virtual background type.
    // The MobileRTCVirtualBGImageInfo has a isSelect property to indicate if the current virtual background is selected.
}

// To add virtual background to list, first check if have permission to add
if meetingService.isAllowToAddNewVBItem() {
    let error = meetingService.addBGImage(UIImage)
}

/*
 To remove a specific virtual background from the list.
 Note: You cannot remove NONE and BLUR type.
 */
meetingService.removeBGImage(MobileRTCVirtualBGImageInfo)

// To set a specific virtual background
meetingService.useBGImage(MobileRTCVirtualBGImageInfo)
```

```objectivec
// To list available virtual background
NSArray *listOfVirtualBG = [meetingService getBGImageList];
if (listOfVirtualBG != nil) {
    // This list will contained a NONE, BLUR or Item (self added) virtual background type.
    // The MobileRTCVirtualBGImageInfo has a isSelect property to indicate if the current virtual background is selected.
}

// To add virtual background to list, first check if have permission to add
if ([meetingService isAllowToAddNewVBItem]) {
    [meetingService addBGImage:UIImage];
}

/*
 To remove a specific virtual background from the list.
 Note: You cannot remove NONE and BLUR type.
 */
[meetingService removeBGImage:MobileRTCVirtualBGImageInfo];

// To set a specific virtual background
[meetingService useBGImage:MobileRTCVirtualBGImageInfo];
```

Users can preview the virtual background.

```swift
if let previewView: UIView = meetingService.previewView {
    // Preview view is available, add previewView to your UIView

    // Start Preview
    meetingService.startPreview(withFrame: CGRect)

    // Stop Preview
    meetingService.stopPreview()
}
```

```objectivec
UIView *previewView = meetingService.previewView;
if (previewView != nil) {
    // Preview view is available, add previewView to your UIView

    // Start Preview
    [meetingService startPreviewWithFrame:CGRect];

    // Stop Preview
    [meetingService stopPreview];
}
```

Users can also have green screen support for virtual backgrounds, but this functionality is only available for iPads.

```swift
/*
 For green background, there are these 3 methods available
 Note: Only iPad support virtual background green screen, iPhone does not support this feature.
 */
meetingService.isUsingGreenVB()
meetingService.enableGreenVB(Bool)
meetingService.selectGreenVBPoint(CGPoint)
```

```objectivec
/*
 For green background, there are these 3 methods available
 Note: Only iPad support virtual background green screen, iPhone does not support this feature.
 */
[meetingService isUsingGreenVB];
[meetingService enableGreenVB:BOOL];
[meetingService selectGreenVBPoint:CGPoint];
```

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