"for in" objective c empty array - objective-c

Question

I came to notice that executing a for/in operation in objective c on an initialized empty NSMutableArray was not working as expected.
Simplified code is :
+(void) convertArray: (NSMutableArray*)arrayIN {
NSMutableArray *arrayOUT = [NSMutableArray array];
NSLog(#"is nil %d - count %d", !arrayIN, [arrayIN count]);
for(NSObject *o in arrayIN)
[arrayOUT addObject:[o convertToAnotherClass]];
}
Actual code is :
+(BOOL) writeTasks: (NSArray*)tasksArray {
NSMutableArray *arr = [NSMutableArray array];
NSLog(#"is nil %d - count %d", !arr, [arr count]);
for(Task *t in tasksArray)
[arr addObject:[t getDictionary]];
NSError *error;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:arr options:NSJSONWritingPrettyPrinted error:&error];
if (! jsonData) {
NSLog(#"Got an error: %#", error);
return NO;
} else {
//NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
[jsonData writeToFile:path options:NSDataWritingAtomic error:nil];
return YES;
}
}
the suprising thing is that executing [dummyClass convertArray:[NSMutableArray array]] is showing this :
2012-06-25 13:51:34.236 Planorama[740:707] is nil 0 - count 0
2012-06-25 13:51:34.239 Planorama[740:707] -[__NSArrayM convertToAnotherClass]: unrecognized selector sent to instance 0xde9b580
(lldb)
Why ? arrayIN is empty, why is convertToAnotherClass even called ?

Answer 1

if you use the block based enumeration it will work the way you want.
Also, the output indicates that o is set to some instance of something, so you may have another problem.
Elegant way to get all objects of a specific type in an Objective-C array
Lastly, it looks like this is a static method, but your example calls it as an instance method.

Answer 2

As Joshua Smith pointed out : I am not checking the count of the iterated array. The iterated array was not empty and contained itself because if a mistyped line :
[tasks addObject:tasks]
instead of
[tasks addObject:task]
in a previous method..
Thanks everyone !
PS : the link of Joshua Smith is very useful ! Future readers : check it out !