Assign optional return value to variable

Question

I have a method which can return nil. If it doesn't return nil, it should replace a local variable:

NSString *errorMsg = error.localizedDescription;
if([self errorMsgFromErrorCode:error.code]) {
    errorMsg = [self errorMsgFomErrorCode:error.code];
}

Is there a smarter more compact way to do this without having to call this helper method twice?

LDNZh · Accepted Answer · 2016-01-19 11:49:54Z

6

errorMsg = [self errorMsgFromErrorCode:error.code] ?: error.localizedDescription;

answered Jan 19, 2016 at 11:49

LDNZh

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2 Comments

Hamish Over a year ago

love the compactness of the ternary operator

SPQR3 Over a year ago

Thanks, I didn't know the ternary operator worked this way when the second parameter is omitted. More info: stackoverflow.com/questions/3319075/…

Sahil · Accepted Answer · 2016-01-19 12:05:59Z

0

you can use conditional operator:

NSString *errormessage = [self errorMsgFromErrorCode:error.code] ? [self errorMsgFromErrorCode:error.code] : error.localizedDescription;

and in swift the shortest form is nil coalescing operator (??) for e.g

var perhapsInt: Int?
let definiteInt = perhapsInt ?? 2
print(definiteInt) // prints 2 
perhapsInt = 3
let anotherInt = perhapsInt ?? 4
print(anotherInt) // prints 3

answered Jan 19, 2016 at 12:05

Sahil

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