iOS 判断是否连接VPN

由于项目测试当中需要外网测试人员连到内网进行测试，有时候因为测试人员大意，没有连接到VPN环境，导致反馈过来的测试结果不正确，因此需要在打包测试安装包的时候先判断是否已经连接上VPN。

网上找到的blog都是判断当前网络状态，但是判断的结果却不准确，满足不了需求。在一次跟 @黄二百万 聊天中获得灵感，可以根据状态栏中的的图标进行判断，判断当前的状态栏是否有VPN标志。
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</br>方案一：起初想通获取状态栏UIStatusBar的方式，将UIView转成UIImage,然后通过图片文字识别，是否包含“VPN”字样，但是系统的UIStatusBar“直接”获取是获取不到的，该方案行不通。（勘误：可以通过方案三中的方式得到）
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</br>方案二：将整个屏幕截图包括状态栏，然后截取

[UIApplication sharedApplication].statusBarFrame 

这个size下的context再转成UIImage，然后通过图片文字识别，是否包含“VPN”字样。但是通过代码截图的方式获取不到带状态栏的截图，因此该方案也行不通（如果谁知道如何获取带状态栏的截图，麻烦留言区告知，谢谢！！！）
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</br> 方案三：偶然看到一篇博客里面可以通过UIApplication的:

- (nullable id)valueForKey:(NSString *)key;

的方式获取到 UIStatusBar！

将手机连上VPN, 尝试打印：

 UIApplication *app = [UIApplication sharedApplication];
 UIView *statusView = [app valueForKey:@"statusBar"];
 NSArray *subViews = [[statusView valueForKey:@"foregroundView"] subviews];
 
 NSLog(@"%@",subViews);

结果如下是:

Printing description of subViews:
<__NSArrayM 0x170258780>(
<UIStatusBarSignalStrengthItemView: 0x100306110; frame = (6 0; 35 20); userInteractionEnabled = NO; layer = <CALayer: 0x17403a0e0>> [Item = <UIStatusBarItem: 0x17403a0c0> [UIStatusBarSignalStrengthItemView (Left)]],
<UIStatusBarServiceItemView: 0x1002015d0; frame = (44 0; 50 20); userInteractionEnabled = NO; layer = <CALayer: 0x17003e520>> [Item = <UIStatusBarItem: 0x17003e560> [UIStatusBarServiceItemView (Left)]],
<UIStatusBarDataNetworkItemView: 0x100209210; frame = (99 0; 13 20); userInteractionEnabled = NO; layer = <CALayer: 0x17003e180>> [Item = <UIStatusBarItem: 0x17003e2e0> [UIStatusBarDataNetworkItemView (Left)]],
<UIStatusBarIndicatorItemView: 0x1002099b0; frame = (118 0; 20 20); userInteractionEnabled = NO; layer = <CALayer: 0x1702204e0>> [Item = <UIStatusBarItem: 0x170220500> [UIStatusBarIndicatorItemView:VPN (Left/Right)]],
<UIStatusBarBatteryItemView: 0x10020a140; frame = (337 0; 33 20); userInteractionEnabled = NO; layer = <CALayer: 0x170220320>> [Item = <UIStatusBarItem: 0x170220580> [UIStatusBarBatteryItemView (Right)]],
<UIStatusBarBatteryPercentItemView: 0x10020bbd0; frame = (303 0; 31 20); userInteractionEnabled = NO; layer = <CALayer: 0x170220c20>> [Item = <UIStatusBarItem: 0x170220560> [UIStatusBarBatteryPercentItemView (Right)]],
<UIStatusBarIndicatorItemView: 0x100209420; frame = (287 0; 10 20); userInteractionEnabled = NO; layer = <CALayer: 0x170220c60>> [Item = <UIStatusBarItem: 0x170220540> [UIStatusBarIndicatorItemView:Alarm (Right)]],
<UIStatusBarIndicatorItemView: 0x10020aaf0; frame = (261 0; 20 20); alpha = 0; userInteractionEnabled = NO; layer = <CALayer: 0x170220d80>> [Item = <UIStatusBarItem: 0x170220500> [UIStatusBarIndicatorItemView:VPN (Left/Right)]],
<UIStatusBarIndicatorItemView: 0x10020a370; frame = (269 0; 12 20); userInteractionEnabled = NO; layer = <CALayer: 0x170220d00>> [Item = <UIStatusBarItem: 0x170220520> [UIStatusBarIndicatorItemView:RotationLock (Right)]],
<UIStatusBarTimeItemView: 0x100204470; frame = (161 0; 56 20); userInteractionEnabled = NO; layer = <CALayer: 0x170220f40>> [Item = <UIStatusBarItem: 0x17403a0a0> [UIStatusBarTimeItemView (Center)]]
)

可以看到description打印结果中有暴露“VPN”相关的信息，证明通过访问私有属性是可以做到的。

方法一：因此可以通过遍历UIStatusBar的子view，打印子view的description，通过判断description中是否包含“VPN”这个子字符串的方式达到文章开头提到的目的！

上代码:

- (BOOL)isVPNConnected {
    UIApplication *app = [UIApplication sharedApplication];
    UIView *statusView = [app valueForKey:@"statusBar"];
    NSArray *subViews = [[statusView valueForKey:@"foregroundView"] subviews];
    
    Class StatusBarIndicatorItemViewClass = NSClassFromString(@"UIStatusBarIndicatorItemView");
    for (UIView *subView in subViews) {
        Class SubStatusBarIndicatorItemViewClass = [subView class];
        if ([SubStatusBarIndicatorItemViewClass isSubclassOfClass:StatusBarIndicatorItemViewClass]) {
            return [[subView description] containsString:@"VPN"];
        }
    }
    return NO;
}

方法二：访问UIStatusBarIndicatorItemView的私有属性_visible判断是否开启了VPN
上代码:

- (BOOL)isVPNConnected {
    UIApplication *app = [UIApplication sharedApplication];
    UIView *statusView = [app valueForKey:@"statusBar"];
    NSArray *subViews = [[statusView valueForKey:@"foregroundView"] subviews];
    
    Class StatusBarIndicatorItemViewClass = NSClassFromString(@"UIStatusBarIndicatorItemView");
    for (UIView *subView in subViews) {
        Class SubStatusBarIndicatorItemViewClass = [subView class];
        if ([SubStatusBarIndicatorItemViewClass isSubclassOfClass:StatusBarIndicatorItemViewClass]) {
            return [[subView valueForKey:@"_visible"] boolValue];
        }
    }
    return NO;
}