Naming of formal parameters in setters with synthesized properties [duplicate] - objective-c

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Good practice for disambiguating argument names versus instance variable names in Objective-C
(3 answers)
Closed 9 years ago.
I have been learning and using Objective-C for quite some time now (it also kind of was my first OOP language) and I finally would like to know how to correctly name synthesized properties.
Let's take the following scenario:
I have got a property called someVariable.
#property (nonatomic, retain) NSString *someVariable;
and synthesize it
#synthesize someVariable;
How would the custom setter look like conventionally ?
1)
I would go ahead and say something like
-(void)setSomeVariable:(NSString *)someVar{
//input parameter MAY sound/look foreign due to the difference to the property
someVariable = someVar;
}
2) (illegal)
But I would like to name the formal parameter just like the property for the sake of readability and convenience. More like in Java like this:
-(void)setSomeVariable:(NSString *)someVariable{
//obviously illegal because this would call the setter over and over again
self.someVariable = someVariable;
}
3) (unconventional)
and according to what I have been reading in the past this
#synthesize someVariable = _someVariable;
is said to be unconventional and not supposed to be used.
So, am I correct in concluding that the way I have been doing it until now, is the only way to create a custom setter ?

Answer 1

3) is not unconventional, it's exactly what the compiler does if you don't provide the #synthesize statement.
This means that, without the #synthesize statement and the ivar declaration, you have an implicit ivar named _someVariable, and a custom setter would usually have a parameter named someVariable
-(void)setSomeVariable:(NSString *)someVariable {
_someVariable = someVariable;
}
Also note that providing custom setter and getter methods for a particular property indicates to the Xcode compiler to not provide the implicit ivar (here _someVariable). In the case of readonly properties, the same if true if you provide just the getter method.
WWDC 2012 session 405 provides a lot of details around Objective-C constructs for modern versions of the compiler.
EDIT
As H2CO3 has suggested in his answer, the code I wrote assumes you're using ARC. If you are using MRC, the setter method would rather be :
-(void)setSomeVariable:(NSString *)someVariable {
[someVariable retain];
[_someVariable release];
_someVariable = someVariable;
}