Dynamically creating getters and setters for #dynamic properties causing infinite loop - c++

Question

Currenlty I have an issue with ocmock for unit testing because some #dynamic properties have no getters or setters when being mocked. I'm using class_addmethod to add the getters and setters for all #dynamic properties. My issue is this
void accessorSetter(id self, SEL _cmd, id newValue)
{
NSString *method = NSStringFromSelector(_cmd);
id value = [newValue copy];
// remove set prefix from string
NSString *anID = [[method stringByReplacingCharactersInRange:NSMakeRange(0, 3) withString:#""] stringByReplacingOccurrencesOfString:#":" withString:#""];
anID = [anID stringByReplacingCharactersInRange:NSMakeRange(0,1) withString:[[anID substringWithRange:NSMakeRange(0, 1)] lowercaseString]];
[self setValue:value forKey:anID];
}
causes an infite loops since setValue calls the setter. I think I can use c++ syntax like self->somevar = value to avoid the infinite loop. My question is how do I do this assigment when the name of the variable is a string? anID is the name of the variable and i can't do self->anID = aValue cuz anID is not a property. How do I convert it to a variable name? Or how can I set the property without creating the infinite loop?

Answer 1

You can use object_setInstanceVariable or object_setIvar and object_getInstanceVariable. You can take a look at the Objective C Runtime Reference for more information.
EDIT:
If you are using ARC, you can't use object_setInstanceVariable. You'll be stuck with object_setIvar.
EDIT 2: See this answer if you are using ARC.
Example usage:
#import <Foundation/Foundation.h>
#import <objc/runtime.h>
#interface Test : NSObject
#property (nonatomic, strong) NSString *test;
#end
#implementation Test
- (id)init {
if (self = [super init]) {
self.test = #"asdasd";
}
return self;
}
- (void)setTest:(NSString*)test {
Ivar var_desc = object_getInstanceVariable(self, [#"_test" cStringUsingEncoding:NSUTF8StringEncoding], NULL);
NSLog(#"Setting _test to %#", test);
object_setIvar(self, var_desc, test);
}
#end
int main(int argc, char *argv[])
{
Test *tst = [[Test alloc] init];
NSLog(#"prop: %#", tst.test);
return 0;
}
Output:
2013-12-11 18:19:32.038 ivar_tst[97090:507] Setting _test to asdasd
2013-12-11 18:19:32.040 ivar_tst[97090:507] prop: asdasd