How long does it take to become an iPhone/IOS developer?

I know a little bit C and some Actionscript3. How long will you estimate that it will take me to become an iPhone developer and be able to post some apps on the Apple store. I plan to learn the IOS platform about 4h/ day in average.
PS: Please let me know why this simple program does not show the output when I'm using scanf with %1 or %d. I have no errors from the compiler. Thanks for your time guys.

The program runs without any errors or warning, however when I type a number
it does not show the output. (thank you for your help) Here's my code:

# import < foundation/foundation.h>

@ interface Person: NSObject {

int age;

}

-(void) print;

@end

@implementation Person

-(void) print {

NSLog (@" Enter a number please ");
scanf ("i", &age);
NSLog (" your number is: ", age);

}
@end

int main ( int argc, char * argcv []) {
NSAutoreleasepool *pool = [ [ NSAutoreleasepool alloc] initi];

Person *Fred;
Fred= [Person alloc];

[Fred print];
[Fred release];

[pool drain];

return 0;

Listen you have take time to be a good an iPhone/ IOS developer. It depend upon you how you learn. If you want to know more about iPhone then please visit some learning site.

Your code have some error please verify it.