Synthesized getter not working for instance variables of type NSString

Question

Hi I'm a newbie in Objective-C programming. Today I was writing a program and I'm quite confused with the way it behaves. Here is the program :

#import <Foundation/Foundation.h>
@interface MyClass:NSObject
{
    NSString * str;
}
@property NSString * str;
@end;

@implementation MyClass
@synthesize str;
@end

int main()
{   NSAutoreleasePool * pool = [[NSAutoreleasePool alloc]init];
    MyClass * obj = [[MyClass alloc]init];
    [obj setStr: @"hello"];
    /* the following lines of code will give error if not commented but why it is                    
     resulting in error  ?????
      NSLog(@"Str = %@",[obj getStr]); // **gives error if not commented** 
      **or**
      NSString * temp;
      temp = [obj getStr]; // gives error
      NSLog(@"%@",temp);
    */
    NSString * temp;
    temp = obj.str;
    NSLog(@"%@",temp); // works just fine 
    [pool drain];
    return 0;
}

In main function when I try to print the str value using getStr a synthesized accessor it gives me error. Why so? Are we not allowed to use synthesized getter for NSString or am I not using the getter in a correct way?? But still the synthesized setter [obj setStr] sets the value for NSString type. I saw some answers here and there for this kind of questions on stack overflow but I really din't understand the answer which were provided there so please explain this in a simple manner for me. Many thanks.

Answer 1

The name of the synthesized getter for property xyz is the same as the name of the property, i.e. xyz. It is not getXyz. Only the setter gets prefixed with a "set", becoming setXyz:

That is why your code

NSLog(@"Str = %@",[obj getStr]);

does not compile. Changing to

NSLog(@"Str = %@",[obj str]);

will fix the problem.

Note: when you let Xcode synthesize a property for you, a variable to "back" that property is also created. You do not need to declare an instance variable str in addition to the property str.

Answer 2

This is not getter method call temp = [obj getStr];. Getter method is trigger by either [obj str]) or dot notation obj.str. But you can define getStr, if you do, then use as you have done.

Answer 3

Another way to access getter and setter of a property:

//getter
NSLog(@"Str = %@",self.str);

//setter
self.str = @"hello";