Question

Possible Duplicate:
Check that an email address is valid on iOS

What is the regex syntax I can use for email validation in iOS for my UITextField.text value? And is there a way for me to check if other UITextField or UITextView is missing?

Can I use this to test for blank values:

if(content.text == nil){
    //do something
}
else{
    //proceed with next course of action
}

Answer 1

To be absolutely sure that you have tested for a blank value, you should also test for an empty string.

This construct does it, and leads to less typing than using isEqualToString:, but it is largely a question of personal preference:

if ( content.text == nil || content.text.length == 0 ) {

}

People with a more intimate knowledge of the Objective-C runtime might point out that testing for nil is redundant, as sending a message to nil will always yield nil (or 0), so content.text.length is nil if content.text is. Also, if your surroundings are populated with hard-core C coders, they could similarly point out that testing for 0 in an if statement is for wimps.

Hence, the typing can be reduced to the following, at the cost of some clarity of your code:

if ( !content.text.length ) {

}

As for a regex to test an email address, there is a good discussion here, and the regex in Cocoa can be done like this:

NSPredicate *regexPred = [NSPredicate predicateWithFormat: @"self matches[cd] '<email regex here>'"];
BOOL match = [regexPred evaluateWithObject: content.text];