objective-c warning ‘class’ may not respond to ‘method’

This is a very interesting error message, you may want to look at the order of the method you are calling, and the code that causes the warning message. 
-(void) aMainMethod{
 [self testMethod] //call the method, warning occurs here
 ....
}
//here's the method you are calling
-(void) testMethod{
  NSLog(@"test");
} 

If  your method is at somewhere after the code you call it (if it’s like above), move it so that it’s before the code (like the code below), and the warning should go away. Even with the warning, you should still be able to compile and run without any problem. 

//here's the method you are calling
-(void) testMethod{
NSLog(@"test");
}
-(void) aMainMethod{
[self testMethod] //no warning
....
}


Here’s an article about this with more details.