之前：
- (void)showTextHud:(NSString*)msg {
MBProgressHUD * hud = [MBProgressHUDshowHUDAddedTo:self.view animated:YES];
hud.mode = MBProgressHUDModeText;
hud.label.text = msg;
hud.margin = 10.0f;
hud.removeFromSuperViewOnHide = YES;
[hud hideAnimated:YESafterDelay:1.5];
}
hud消失后发现webview无法点击，而且有时显示位置不正确
修改：MBProgressHUD*hud = [MBProgressHUDshowHUDAddedTo:[UIApplicationsharedApplication].keyWindowanimated:YES];
