Objective-C arrays, style and spirit - objective-c

Question

Newbie question. Looking at arrays (ie: dynamically sized) this works:
NSArray *array;
array = [NSArray arrayWithObjects:
#"one", #"two", nil];
This does not:
array = [NSArray arrayWithObjects:
1, 2, nil];
Ok, I get it. This works:
array = [NSArray arrayWithObjects:
[NSNumber numberWithInt:1], [NSNumber numberWithInt:2], nil];
Its sorta less "on the fly" as C++ / Java. I see the same thing with the init examples I'm reading. For example:
// pseudo objc example
MyVar v = [MyVar init]; // blank
[v setSomething];
[v setSomethingElse];
// use v down here
In C++/Java I'd do:
MyVar v = new MyVar("foo", "bar", "baz", "quux");
And I'd know that v is ready to go by default. Is there a spirit of ObjC that I should not fight? Should I just expect to write more lines and less "one-liners"?

Answer 1

In Objective-C, the "init" method is just a method. Unlike Java or C++ whose constructors are different than other methods. So you can define your own init methods that behave like C++ or Java constructors. For example, you could define an init method that takes several parameters. It might look something like this.
MyVar* v = [[MyVar alloc] initWithName:#"foo" andTitle:#"bar"];
// do something with v
[v release];
Common practice is to simply create new methods that perform object initialization, and prefix the method name with "init" for clarity and consistency.

Answer 2

NSArray, its modifiable variant NSMutableArray, and all collection structures (NSDictionary, NSSet) are made for storing objects. This is why you see [NSNumber numberWithInt:1] instead of simply 1.
For strings, note that an Objective-c string (like #"one", including leading #) is an object of type NSString, whereas a C string (like "one", without #) is not an object.
If you want the simplicity of storing simple values in arrays, don't forget that Objective-C is a superset of C. This means that you can use a declaration like:
int array[] = { 1, 2, 3 };

Answer 3

What you get with Objective-C's verbosity is greater readability.
Sure, while you're writing code, it might be easy to knock up something like you wrote
MyRect rect = new MyRect(1.0, 1.0, 3.0 3.0);
But when you, or more likely someone else, comes to maintain your code then I would argue that this is much easier to read:
MyRect *rect = [[MyRect alloc] initWithX:1.0 Y:1.0 width:3.0 height:3.0];
And in these days of smart editors it isn't that much harder to write.

Answer 4

You can write constructors that take named parameters to get it down to one line:
MyVar *v = [[MyVar alloc] initWithFoo:#"foo" bar:#"bar" baz:#"baz" quux:#"quux"];

Answer 5

Yeah, Objective-C is pretty verbose, so you're going to need to get used to that.
The MyVar init case is not quite right; you generally need to do a [[MyVar alloc] init] or a [MyVar new]. And in many cases, there are init variants that take arguments, like
MyVar v = [[MyVar alloc] initWithSomething: "foo" somethingElse: "bar"];
If you want something less verbose, where you can get more one liners in, you might want to look into MacRuby, which is a binding between Ruby and Objective-C that gives you access to all of the Cocoa APIs but with a much more compact, high level syntax (and you can go even more compact still with HotCocoa. Of course, there is a bit of a performance penalty using MacRuby, so if you're doing a high performance game it might not be ideal to write your drawing loop in RubyCocoa, but its fine for the vast majority of applications.