Never before seen syntax in Objective-C: open/close braces w/out method/conditional statement, what is the purpose?

Question

I am looking over an Xcode project I downloaded and am seeing code syntax that I am unfamiliar with:

enter image description here

The braces don't belong to a method signature, or any other conditional statement, they are just floating there. What is the point of this? Purely for code segregation/readability purposes?

No, this code is within a method. Was confused about why it would be there, but the below answers make sense. — Lizza, Sep 17 '13 at 16:12
Sometimes I'll use this style to group code visually, not for any semantic purpose... And in switch statements. — lmirosevic, Oct 01 '13 at 07:58

score 7 · Accepted Answer · answered Sep 17 '13 at 16:08

7

This is just block scope; and is the same in C and C++. Any variables declared within the block are inaccessible outside of it. I commonly use it in switch statements:

switch(x) {
case 1: {
    const char *s = "hi";
}
break;
case 2: {
    const char *s = "ho";
}
break;
// etc.
}

Note that there are two variables called s, neither of which interfere with the other as they are within their own scope.

answered Sep 17 '13 at 16:08

trojanfoe

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I guess I commonly use it in switch statements as well! Didn't know it could be used anywhere. Thanks for the info. – Lizza Sep 17 '13 at 16:11
@Casper Yeah you can, as your question demonstrates, but for me it's not so common. – trojanfoe Sep 17 '13 at 16:11
it is common to use it with `if` statements too – progrmr Sep 17 '13 at 22:36

score 2 · Answer 2 · answered Sep 17 '13 at 16:10

The declarations within the scope enclosed by the braces will be confined to that scope, so label, icon, and button will not be visible outside of it. As such it provides locality which is generally considered to be good.

score 1 · Answer 3 · edited May 23 '17 at 10:32

1

Legacy code needed { } in order to do declarations at all

In C89, you couldn't just do int i; anywhere; declarations were only valid at the beginning of blocks.

check this for more explanation

Why enclose blocks of C code in curly braces?

edited May 23 '17 at 10:32

Community

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answered Sep 17 '13 at 16:08

Priyatham51

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Never before seen syntax in Objective-C: open/close braces w/out method/conditional statement, what is the purpose?

3 Answers3