Objective C - Safely create a static Boolean?

Question

I want to have a static boolean like in Java. This boolean only created once for the entire class, no matter how many instance it has.

I read some posts here. Some of them are suggesting that in .m file, init this variable like

static BOOL myBool = NO;

and then have a getter and a setter function. But I was told that this is not safe and clean in Objective C. A safer and cleaner way to do this is init static variable in function. But if I init it in a function, like

+(Bool)getMyBool {
    static BOOL myBool = NO;
    return myBool;
}

In this way myBool will always NO. What if I want to set this boolean afterwards? If I call static BOOL myBool again, would it give me the same boolean?

"In this way myBool will always NO." – you seem to have missed the point of `static`. — The Paramagnetic Croissant, Jul 10 '15 at 16:04
The original code is absolutely fine. Whoever told you it's not safe and clean suffers from some object-oriented illness. — gnasher729, Jul 10 '15 at 19:04

score 2 · Answer 1 · edited May 23 '17 at 11:51

2

There is nothing inherently “not safe and clean” about a global static variable in Objective-C and they are commonly used when appropriate - they are effectively Objective-C's class variables.

See Setting Static Variables in Objective-C for one way to write the getter and setter functions you mention.

edited May 23 '17 at 11:51

Community

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answered Jul 10 '15 at 17:46

CRD

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katie · Accepted Answer · 2015-07-10T18:59:47.123

0

Try this

+(BOOL)resetBoolOrGet:(BOOL)reset newVal:(BOOL)newValue {
    static BOOL myBool = NO;
    if (reset) {
        myBool = newValue;
    }
    return myBool;
}

So, if you want to assign a new value to this boolean, call

[MyClass resetBoolOrGet:YES newVal:newValue];

If you only wants to get the value of that static boolean, call

[MyClass resetBoolOrGet:NO newVal:(either YES or NO)];

edited Jul 10 '15 at 18:59

answered Jul 10 '15 at 16:13

katie

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`bool` is a typename in C and C++, don't use it as a variable name. – The Paramagnetic Croissant Jul 10 '15 at 16:18
That'll work, but I don't see the point of it all unless you really want access to that BOOL from outside the compilation unit. – bbum Jul 10 '15 at 21:27

Objective C - Safely create a static Boolean?

2 Answers2