Here is a quick and simple way to validate an email address in iOS.

Validate an email (iOS)

//Place outside any other methods
- (BOOL)validateEmail:(NSString *)emailStr {
NSString *emailRegex = @"[A-Z0-9a-z._%+-]+@[A-Za-z0-9.-]+\\.[A-Za-z]{2,4}";
NSPredicate *emailTest = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", emailRegex];
return [emailTest evaluateWithObject:emailStr];
}

//Place where you wish to validate the email
if(![self validateEmail:[emailAddress text]]) {
 //Didn't enter correct email value
} else {
    //Did enter correct email value
}