FSPageContentView这个库需要修改源码才能用，否则有黑屏bug

- (instancetype)initWithFrame:(CGRect)frame childVCs:(NSArray *)childVCs parentVC:(UIViewController *)parentVC delegate:(id<FSPageContentViewDelegate>)delegate
{
    self = [super initWithFrame:frame];
    if (self) {
        self.parentVC = parentVC;
        self.childsVCs = childVCs;
        self.delegate = delegate;
        
//        [self setupSubViews]; //去掉这个,否则黑屏
    }
    return self;
}