Objective C calling method dynamically with a string

Question

Im just wondering whether there is a way to call a method where i build the name of the method on the fly with a string.

e.g. I have a method called loaddata

-(void)loadData;

to call this i would normally call it like

[self loadData];

But i want to be able to call it dynamically with a string e.g.

NSString *methodName = [[NSString alloc] initWithString:@"loadData"];
[self methodName];

This is a stupid example but i hope you get my point. I am using it for databinding classes that I am setting up for my IPad application. Hard to explain but to get it to fire I need to work out how to call a method with a string.

Any ideas?

Thanks

The method I want to call is a function that returns an NSString. — IPadHackAndSlash
– IPadHackAndSlash, Commented Dec 15, 2010 at 5:23

shreyasva · Accepted Answer · 2010-12-15 05:12:38Z

110

You can try something like

SEL s = NSSelectorFromString(selectorName);
[anObject performSelector:s];

answered Dec 15, 2010 at 5:12

shreyasva

13.7k26 gold badges82 silver badges103 bronze badges

Sign up to request clarification or add additional context in comments.

5 Comments

IPadHackAndSlash Over a year ago

In this situation the method returns a value which is an NSString in one case. I get an error saying Lvalue required as left operand of assignment. This is my code: SEL s = NSSelectorFromString(@"getIDString"); [self text] = [boundEntity performSelector:s];

Ishu Over a year ago

what is [self text],where you assign the value return getIDString.

shreyasva Over a year ago

[boundEntity performSelector:s] returns a value of type that does not match the type of [self text]. I think you need to set @property for text and call [self setText:[[boundEntity performSelector:s]]].

malhal Over a year ago

performSelector may cause a leak because selector is unknown!

NedStarkOfWinterfell Over a year ago

stackoverflow.com/questions/7017281/…

Adam Milligan · Accepted Answer · 2010-12-15 05:16:40Z

13

You can use the objc_msgSend function. It takes two parameters, the receiver and the selector to send to it:

objc_msgSend(self, someSelector);

You'll need to turn your string into the appropriate selector using NSSelectorFromString:

NSString *message = [self getSomeSelectorName];
objc_msgSend(self, message);

The method also takes a variable number of arguments, so you can send messages with any number of arguments.

NSString *message = [self getSomeSelectorNameWithManyArguments];
objc_msgSend(self, message, arg1, arg2, arg3, arg4);

answered Dec 15, 2010 at 5:16

Adam Milligan

2,82621 silver badges17 bronze badges

Collectives™ on Stack Overflow

Objective C calling method dynamically with a string

2 Answers 2

5 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

5 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related