CODEWITHSUNDEEP
iosuialertview
user1046037
user1046037

Reputation: 17695

Check if message is empty before displaying UIAlertView

UIAlertView is widely used in the code.

I would like to check all alert view message before displaying it.

I have written a method in a category of UIAlertView.

Question:

Note - I have already a method for this, but I don't want to change the code manually in all the places, instead I am looking for a sleek solution if that is possible such that I change in one place (like override a method)

Upvotes: 1

Views: 275

Answers (1)

cncool
cncool

Reputation: 1026

Create a category on UIAlertView and provide a method that checks first if the message exists, then shows:

@implementation UIAlertView (OnlyShowIfMessageExists)

- (void)override_show
{
    if(self.message.length)
    {
        [self override_show];
    }
}

It is calling override_show and not show, because those methods will be swizzled.

Implement the +(void)load method as well in the category, and swizzle your method with the show method:

+(void)load
{
    SEL origSel = @selector(show);
    SEL overrideSel = @selector(override_show);

    Method origMethod = class_getInstanceMethod(UIAlertView.class, origSel);
    Method overrideMethod = class_getInstanceMethod(UIAlertView.class, overrideSel);

    if(class_addMethod(UIAlertView.class, origSel, method_getImplementation(overrideMethod), method_getTypeEncoding(overrideMethod)))
    {
        class_replaceMethod(UIAlertView.class, overrideSel, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    }
    else
    {
        method_exchangeImplementations(origMethod, overrideMethod);
    }
}

@end

Now, all calls to show on a UIAlertView will be using your method override_show.

http://www.mikeash.com/pyblog/friday-qa-2010-01-29-method-replacement-for-fun-and-profit.html

Upvotes: 1

Related Questions