Can anyone explain why this works in Objective-C? I would expect it to give an error since an object is being assigned to an int variable. I get that it does work, and this is great, but I am missing why this is allowed?
int i = [NSNumber numberWithInt:123];
Furthermore, this seems to store the wrong value (ie, on my system when I print out the value of "i" using NSLog I get "252711" instead of 123); however, only when the variable is declared and assigned in my main code. If I declare it as an instance variable of an object and then use Key-Value coding to assign it a value, it works properly:
Object instance variables...
@interface myObject : NSObject
{
int anInt;
}
Main code...
[myObject setValue:[NSNumber numberWithInt:123] forKey:@"anInt"];
NSLog(@"%@", [myObject valueForKey:@"anInt"]);
This code prints out "123" as expected, but I'm not sure why given that when using a seemingly similar approach above it does not work properly.
it doesnt "work" and there is a compiler warning about it. the reason it can be compiled is that the NSNumber class method numberWithInt returns a pointer, which can be implicitly converted to int. When you print it out you are getting the address where the objective-c object was allocated.
the SetValue:forKey: method doesnt take an int parameter, it takes an id which is just a pointer to a generic Objective-C object. Key-Value coding is taking care of assigning the intValue of the NSNumber object for you.