No visible #interface for 'InstanceName' declares the selector' - automatic-ref-counting

Question

My name is Bob. I code for the Parks Department of NYC. I'm starting to learn Objective C and have a "Semantic Issue." I must have a blind spot, because I checked all the following code and don't see the problem. Thank you for ant help you can give
"No visible #interface for 'Greeter' declares the selector 'setGreetingText::"
#import <Foundation/Foundation.h>
#import "Greeter.h"
int main (int argc, const char * argv[])
{
#autoreleasepool {
Greeter* myGreeter = [[Greeter alloc] init];
// error on this line
[myGreeter setGreetingText: #"Hello Objective-C!!" : #"Hello VIP Objective-C!!"];
[myGreeter issueGreeting];
}
return 0;
}
======================================
import "Greeter.h"
import "NewGreeter.h"
#implementation Greeter
NewGreeter *VTS;
- (NSString*) greetingText
{
return [self greetingText];
}
- (void) setGreetingText:(NSString*) newText01
andThisToo:(NSString*) newText02
{
greetingText = newText01;
[VTS setNewGreetingText: newText02];
}
- (void) issueGreeting
{
NSLog(#"%#", greetingText);
}
#import "NewGreeter.h"
#implementation NewGreeter
- (NSString*) NewGreetingText
{
return greeting;
}
- (void) setNewGreetingText:(NSString*) newText
{
greeting = newText;
}
- (void) issueNewGreeting
{
NSLog(#"%#", [self NewGreetingText]);
}
#end
#import <Foundation/Foundation.h>
#import "NewGreeter.h"
#interface Greeter : NSObject
{
NSString *greetingText;
}
- (void) setGreetingText:(NSString*) newText01
andThisToo:(NSString*) newText02;
- (NSString*) greetingText;
- (void) setGreetingText:(NSString*) newText;
- (void) issueGreeting;
#import <Foundation/Foundation.h>
#interface NewGreeter : NSObject
{
NSString *greetingText;
}
- (NSString*) NewGreetingText;
- (void) setNewGreetingText:(NSString*) newText;
- (void) issueNewGreeting;
#end
#import <Foundation/Foundation.h>
#interface NewGreeter : NSObject
{
NSString *greetingText;
}
- (NSString*) NewGreetingText;
- (void) setNewGreetingText:(NSString*) newText;
- (void) issueNewGreeting;
#end

Answer 1

You implement the method named -setGreetingText:andThisToo:, but you're trying to use it incorrectly. You need to change your call to:
[myGreeter setGreetingText: #"Hello Objective-C!!" andThisToo:#"Hello VIP Objective-C!!"];
Notice the andThisToo bit.
If you're only trying to set your object's properties, then you don't need to expose custom methods for that. Instead, you could do:
// In Greeter.h
#interface Greeter: NSObject
#property NSString *greetingText;
#end
// In Greeter.m
#implementation Greeter
#synthesize greetingText = _greetingText; // Create a backing instance variable
#end
This creates an instance variable setter method named setGreetingText and an instance variable getter named greetingText. I'd recommend you read up on creating object properties.