info.plist文件中添加
NSExtensionUsageDescription：此应用需要访问扩展功能实现安全录屏

实现方式一： UIScreenCapturedDidChangeNotification

录屏开启时，画面黑屏，声音可录入

.h
/// 安全录屏的黑色视图
@property (nonatomic, strong) UIView *safeScreenView;
.m
// 安全录屏
- (UIView *)safeScreenView {
    if (!_safeScreenView) {
        _safeScreenView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, KScreenW, KScreenH)];
      
        [_safeScreenView setUserInteractionEnabled:NO];
        _safeScreenView.backgroundColor = [UIColor blackColor];
        [_safeScreenView setMultipleTouchEnabled:NO];
    }
    return  _safeScreenView;
}

- (void)showSafeScreen {
    [self.window addSubview:self.safeScreenView];
    [self.window bringSubviewToFront:self.safeScreenView];
    [self.safeScreenView setHidden: NO];
}

- (void)hideSafeScreen {
    [self.safeScreenView setHidden: YES];
}

对于直播间内，涉及到 推拉流问题，最好不要对声道进行处理

#pragma mark- 安全录屏
- (void)handleSafeScreen {
//    AVAudioSession * session = [AVAudioSession sharedInstance];
//    @try {
//        [session setCategory: AVAudioSessionCategoryPlayAndRecord mode:AVAudioSessionModeDefault options: AVAudioSessionCategoryOptionMixWithOthers error:nil];
//        [session setActive:YES error:nil];
//    } @catch (NSException *exception) {
//        NSLog(@"安全录屏配置音频会话失败:%@", exception.reason);
//        [NetRequest postLog:[NSString stringWithFormat: @"安全录屏配置音频会话失败:%@", exception.reason] isFailure:true];
//    }
    
    [NSNotificationCenter.defaultCenter addObserver:self selector:@selector(screenListenUpdate) name:UIScreenCapturedDidChangeNotification object:nil];
    [self screenListenUpdate];
}

- (void)screenListenUpdate {
    BOOL isSafeSwith = NO;
    /// 0不可以录屏  1可以录屏
    if (UIScreen.mainScreen.isCaptured && self.baseModel.user_extra_info != nil && self.baseModel.user_extra_info.is_screen_safe_switch == 0) {
        isSafeSwith = YES;
    }
    AppDelegate *delegate = (AppDelegate *)UIApplication.sharedApplication.delegate;
    
    if (isSafeSwith == YES) {
        [delegate showSafeScreen];
        NSLog(@"开启安全录屏");
        
    } else {
        NSLog(@"关闭安全录屏");
        [delegate hideSafeScreen];
    }
}

实现方式二 ，通过UITextField，将无法截屏的页面添加至SafeView上

在UIViewContoller中

let secureTextField = SafeView(frame: .zero)
override func loadView() {
        view = secureTextField
    }

其中关于SafeView的完整实现代码

class SafeView: UIView {
    
    private var safeZone: UIView?
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        safeZone = makeSecureView(secureEnabled: true)
        safeZone?.autoresizingMask = [.flexibleWidth, .flexibleHeight]
        self.addSubview(safeZone!)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func makeSecureView(secureEnabled: Bool) -> UIView {
        let tf = UITextField(frame: self.frame)
        tf.isSecureTextEntry = secureEnabled
        let secureView = tf.subviews.first

        secureView?.isUserInteractionEnabled = true

        secureView?.subviews.forEach { $0.removeFromSuperview() }
        
        return secureView ?? UIView(frame: self.frame)
    }
    
    public override func addSubview(_ view: UIView) {
        guard
            let safe = safeZone,
            view != safeZone
        else {
            super.addSubview(view)
            return
        }
        safe.addSubview(view)
    }
    
    public override func insertSubview(_ view: UIView, belowSubview siblingSubview: UIView) {
        guard
            let safe = safeZone,
            view != safeZone
        else {
            super.insertSubview(view, belowSubview: siblingSubview)
            return
        }
        safe.insertSubview(view, belowSubview: siblingSubview)
    }
    
    public override func insertSubview(_ view: UIView, aboveSubview siblingSubview: UIView) {
        guard
            let safe = safeZone,
            view != safeZone
        else {
            super.insertSubview(view, aboveSubview: siblingSubview)
            return
        }
        safe.insertSubview(view, aboveSubview: siblingSubview)
    }
    
    public override func insertSubview(_ view: UIView, at index: Int) {
        guard
            let safe = safeZone,
            view != safeZone
        else {
            super.insertSubview(view, at: index)
            return
        }
        safe.insertSubview(view, at: index)
    }
    
    public override func exchangeSubview(at index1: Int, withSubviewAt index2: Int) {
        guard
            let safe = safeZone
        else {
            super.exchangeSubview(at: index1, withSubviewAt: index2)
            return
        }
        safe.exchangeSubview(at: index1, withSubviewAt: index2)
    }
    
    public override func bringSubviewToFront(_ view: UIView) {
        guard
            let safe = safeZone,
            view != safeZone
        else {
            super.bringSubviewToFront(view)
            return
        }
        safe.bringSubviewToFront(view)
    }
    
    public override func sendSubviewToBack(_ view: UIView) {
        guard
            let safe = safeZone,
            view != safeZone
        else {
            super.sendSubviewToBack(view)
            return
        }
        safe.sendSubviewToBack(view)
    }

}