HUD的一种简单的实现 ##用法：
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initWithImage:(UIImage *)image withString:(NSString *)string 生成ASAKHUD实例 -
显示HUD调用ASAKHUDShowWithBlock:(HUDDidShow)showBlock 回调block用来完成一些任务 -
结束HUD时调用ASAKHUDDismissWithBlock:(HUDDidDismiss)dismissBlock 回调block用来完成一些任务 -
(void)ASAKHUDShowWithBlock:(HUDDidShow)showBlk Withduration:(float)duration dismissWithBlock:(HUDDidDismiss)dismissBlk; 设置整个HUD的流程