Funny switch error in iOS

Question

Could you try those two codes ? The first one raises an error, not the second one. I'd like to know if it's because of my XCode version, and if not, why is it happening.

        int typeNumber = 4;
        switch (typeNumber) {
            case typeNumberEvent:
                NSString myString;
                break;
            case typeNumberAd:
                NSURL myURL;
                break;
            default:
                NSNumber myNumber;
                break;
        }

        int typeNumber = 4;
        switch (typeNumber) {
            case typeNumberEvent:
                NSLog(@"hello");
                NSString myString;
                break;
            case typeNumberAd:
                NSLog(@"hello");
                NSURL myURL;
                break;
            default:
                NSLog(@"hello");
                NSNumber myNumber;
                break;
        }

I hope you're writing more code than this. The scope of those variables is pretty limited. — Hyperbole, Aug 30 '11 at 15:46
possible duplicate of [Can I declare variables inside an Objective-C switch statement?](http://stackoverflow.com/questions/1115304/can-i-declare-variables-inside-an-objective-c-switch-statement) — Brad Larson, Aug 31 '11 at 17:24

score 5 · Answer 1 · answered Aug 30 '11 at 15:41

5

The compiler throws error if you try to create a variable at the first line of case.

Just enclose the case block with braces. Everything will be alright.

case typeNumberEvent: {
        NSString myString;
        break;
}

answered Aug 30 '11 at 15:41

EmptyStack

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ok thanks. Do you know why we can't declare a variable at the first line ? Or you just know the remede ? – Nielsou Hacken-Bergen Aug 30 '11 at 15:46
I don't know the reason. But, it seems, this is an intended behaviour of iOS. – EmptyStack Aug 30 '11 at 15:50
I just came across this issue too - it does seem odd behaviour. If it is 'intended behaviour', you think Xcode would give a better error warning. – So Over It Apr 30 '13 at 03:36

score 1 · Accepted Answer · edited May 23 '17 at 11:56

If you declare variables inside a case block, you should declare that block with curly braces. Your example would become:

    int typeNumber = 4;
    switch (typeNumber) {
        case typeNumberEvent:
            {
                NSString myString;
                break;
            }
        case typeNumberAd:
            {
                NSURL myURL;
                break;
            }
        default:
            {
                NSNumber myNumber;
                break;
            }
    }

This answer sums it up nicely, too: Can I declare variables inside an Objective-C switch statement?

Funny switch error in iOS

2 Answers2