UIAlertView大家可能经常用到，但是UIAlertView 没有block功能,的确不方便。故而找到了这个开源项目，
https://github.com/dogo/SCLAlertView
另外，还支持pod，岂不更方便
pod 'SCLAlertView-Objective-C'
SCLAlertView *alert = [[SCLAlertView alloc] init];
//Using Selector
[alert addButton:@"First Button" target:self selector:@selector(firstButton)];
//Using Block
[alert addButton:@"Second Button" actionBlock:^(void) {
NSLog(@"Second button tapped");
}];
//Using Blocks With Validation
[alert addButton:@"Validate" validationBlock:^BOOL {
BOOL passedValidation = ....
return passedValidation;
} actionBlock:^{
// handle successful validation here
}];
[alert showSuccess:self title:@"Button View" subTitle:@"This alert view has buttons" closeButtonTitle:@"Done" duration:0.0f];