Re: Variable Number of Parameters in Method
Re: Variable Number of Parameters in Method
- Subject: Re: Variable Number of Parameters in Method
- From: Alex Zavatone <email@hidden>
- Date: Wed, 21 Aug 2013 15:04:00 -0400
Just in case the styled text is stripped, here is the line I'm referring to from the header file:
+ (id)arrayWithObjects:(id)firstObj, ... NS_REQUIRES_NIL_TERMINATION;
Sent from my iPad
On Aug 21, 2013, at 2:58 PM, Alex Zavatone <email@hidden> wrote:
> The approach I mentioned is what NSArray uses to allow an arbitrary amount of objects in this call to init it. Supplying nil tells the runtime that there are no more parameters.
>
> NSArray *myArray;
> myArray = [NSArray alloc] initWithObjects: @"my String", @"another", @"more", nil];
>
> It's the nil termination of the parameters approach.
>
> How you do this is that bold line that I outlined earlier.
>
> Sent from my iPad
>
> On Aug 21, 2013, at 1:17 PM, "Stephen J. Butler" <email@hidden> wrote:
>
>> On Wed, Aug 21, 2013 at 4:22 AM, Dave <email@hidden> wrote:
>>
>>> if ([myType isEqualToString:@"NSInteger"] )
>>> {
>>> myNSInteger = va_arg(myArgumentList,NSInteger*);
>>> // do something with myNSInteger
>>> [myFormattedString appendFormat:@"myNSInteger = %d ",
>>> myNSInteger];
>>> }
>>>
>>> else if ([myType isEqualToString:@"CGFloat"] )
>>> {
>>> myCGFloat = va_arg(myArgumentList, CGFloat*);
>>> // do something with myCGFloat
>>> [myFormattedString appendFormat:@"myCGFloat = %f ",
>>> myCGFloat];
>>> }
>>
>>
>> This is better, however... if you pass an actual NSInteger or CGFloat to
>> the method, va_arg() should have a type of NSInteger or CGFloat, not
>> pointers to those types. Your code examples with it's printf style formats
>> is using the former, not the latter. Just to be clear, you can have all
>> these cases:
>>
>> if ([myType isEqualToString:@"NSInteger"] ) {
>> myNSInteger = va_arg(myArgumentList,NSInteger);
>> } else if ([myType isEqualToString:@"NSInteger*"] ) {
>> pMyNSInteger = va_arg(myArgumentList,NSInteger*);
>> } else if ([myType isEqualToString:@"CGFloat"]) {
>> myCGFloat = va_arg(myArgumentList, CGFloat);
>> } else if ([myType isEqualToString:@"CGFloat*"]) {
>> pMyCGFloat = va_arg(myArgumentList, CGFloat*);
>> } ... etc
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