How to use performSelector:withObject:afterDelay: with primitive types in Cocoa?

Question

Hi, The NSObject method performSelector:withObject:afterDelay: allows me to invoke a method on the object with an object argument after a certain time. It cannot be used for methods with a non-object argument (e.g. ints, floats, structs, non-object pointers, etc.).

What is the simplest way to achieve the same thing with a method with a non-object argument? I know that for regular performSelector:withObject:, the solution is to use NSInvocation (which by the way is really complicated). But I don't know how to handle the "delay" part.

Thanks,

Answer 1

Just wrap the float, boolean, int or similar in an NSNumber.

For structs, I don't know of a handy sollution, but you could make a separate ObjC class that owns such a struct.

Answer 2

Perhaps NSValue, just make sure your pointers are still valid after the delay (ie. no objects allocated on stack).

Answer 3

Here is what I used to call something I couldn't change using NSInvocation:

SEL theSelector = NSSelectorFromString(@"setOrientation:animated:");
NSInvocation *anInvocation = [NSInvocation
         invocationWithMethodSignature:
         [MPMoviePlayerController instanceMethodSignatureForSelector:theSelector]];

[anInvocation setSelector:theSelector];
[anInvocation setTarget:theMovie];
UIInterfaceOrientation val = UIInterfaceOrientationPortrait;
BOOL anim = NO;
[anInvocation setArgument:&val atIndex:2];
[anInvocation setArgument:&anim atIndex:3];

[anInvocation invoke];

Answer 4

You Could just use NSTimer to call a selector:

[NSTimer timerWithTimeInterval:1.0 target:self selector:@selector(yourMethod:) userInfo:nil repeats:NO]

Answer 5

Pehaps...ok, very likely, I'm missing something, but why not just create an object type, say NSNumber, as a container to your non-object type variable, such as CGFloat?

(sorry, can't do code since the HTML menu bar isn't visible) CGFloat myFloat = 2.0; NSNumber *myNumber = [NSNumber numberWithFloat:myFloat];

[self performSelector:@selector(MyMethod:) withObject:myNumber afterDelay:5.0];

Answer 6

Pehaps...ok, very likely, I'm missing something, but why not just create an object type, say NSNumber, as a container to your non-object type variable, such as CGFloat?

CGFloat myFloat = 2.0; 
NSNumber *myNumber = [NSNumber numberWithFloat:myFloat];

[self performSelector:@selector(MyCalculatorMethod:) withObject:myNumber afterDelay:5.0];