原文：http://cht005288201307234627.iteye.com/blog/1927961
SVProgressHUD和MBProgressHUD效果差不多，不过不需要使用协议，同时也不需要声明实例。
直接通过类方法进行调用即可：
[SVProgressHUD method];
可以使用一下方法显示状态：
+ (void)show;
+ (void)showWithMaskType:(SVProgressHUDMaskType)maskType;
+ (void)showWithStatus:(NSString*)status;
+ (void)showWithStatus:(NSString*)status maskType:(SVProgressHUDMaskType)maskType;
// stops the activity indicator, shows a glyph + status, and dismisses HUD 1s later
//+ (void)showStringWithNoIndicator:(NSString *)status;
+ (void)showSuccessWithStatus:(NSString*)string;
+ (void)showSuccessWithStatusNoAutoDismiss:(NSString *)string;
+ (void)showErrorWithStatusNoAutoDismiss:(NSString *)string;
+ (void)showErrorWithStatus:(NSString *)string;
+ (void)showImage:(UIImage*)image status:(NSString*)status; // use 28x28 white pngs