Objective C - better way to write my if statement [closed] - ios

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It's not an actual problem but it is frustrating me..
I was looking for a better way to right an IF statement with multiple values that can be accepted.
For example:
if ([[myJson objectForKey:#"pages"] intValue] == 0 || [[myJson objectForKey:#"pages"] intValue] == 3)
Isn't there any way to write something like:
if ([[myJson objectForKey:#"pages"] intValue] == 0 | 3)
{
}
Thanks !!

Answer 1

No, not really. You could do this:
int pages = [[myJson objectForKey:#"pages"] intValue];
if (pages == 0 || pages == 3)
That's what I would recommend. The code you posted is both less efficient and harder to maintain than the code I show.
In your code you actually invoke the objectForKey and intValue methods twice on the same object.
Plus if at some point in the future you change the key value, or the variable name, you have to make the same edit in 2 places, which is more work and adds another chance to introduce a new copy/paste error.

Answer 2

In addition to the other valid answers, you could use a switch:
int numberOfPages = [[myJson objectForKey:#"pages"] intValue];
switch (numberOfPages) {
case 0:
case 3: {
NSLog(#"Is 0 or 3");
break;
}
default: {
NSLog(#"Is NOT 0 or 3");
break;
}
}

Answer 3

This is a much better method as it is clean and easier to read:
int x = [[myJson objectForKey:#"pages"] intValue];
if (x == 0 || x == 3) {
}

Answer 4

You are highly optimistic there.
If myJson is not an NSDictionary your app will crash.
If myJson[#"pages"] is not an NSNumber then your app will crash.
If myJson[#"pages"] does not exist then intValue will return 0.
If myJson[#"pages"] has a value of 0.9 or 3.7 then intValue will return 0 or 3.
I suggest you add a category to NSDictionary with a method like integerValueForKey: withDefault where you lookup an item, check that it is an NSNumber with an integer value, return that value or return the default value.

Answer 5

As David Rönnqvist pointed out, it is mostly a matter of preference. I would personally go with NSArray containing allowed values. This way you won't clutter your code with unnecessary intValue calls. Also adding another allowed value will only require adding a single value to an array instead of adding another condition inside if statement.
Note that you can use Objective-C literal syntax to make the code more concise.
NSArray *allowedValues = #[#0, #3];
if([allowedValues containsObject:myJson[#"pages"]]) {
}

Answer 6

If [myJson objectForKey:#"pages"] is an NSNumber. You could do this:
if([#[#0, #3] containsObject:[myJson objectForKey:#"pages"]])
And if myJson is an NSDictionary you could even shorten it to:
if([#[#0, #3] containsObject:myJson[#"pages"]])
It's not necessarily optimal, but it does provide you with a lot more flexibility when adding more values to check against, which it sounds like you're looking for as opposed to the fastest code. If you're just checking a few values I'm assuming speed of execution is not an issue.
Side note: this works because NSArray's containsObject: method calls isEqual: on every object. NSNumber's isEqualToNumber: gets called. This will also work with NSString instead of NSNumber if that's what you're working with. Just change the search array to hold NSString objects in that case.