APP_STATUSBAR_HEIGHT=[UIApplication sharedApplication].statusBarFrame.size.height，包含热点栏（如有）高度，标准高度为20pt，当有个人热点连接时，高度为40pt。
判断 [UIApplication sharedApplication].statusBarFrame.size.height 是否等于40
([UIApplication sharedApplication].statusBarFrame.size.height==40?[UIScreen mainScreen].bounds.size.height-20:[UIScreen mainScreen].bounds.size.height)
