gistfile1.m

// Foo.m:
- (instancetype) initWithResult:(NSTextCheckingResult *)result forLine:(NSString *)line {
  if ( self = [super init] ) {
    // do some stuff
  }
  
  return self;
}

+ (instancetype) parse:(NSString *)line {
  // do some stuff

  return [[self alloc] initWithResult:result forLine:line];
}

// Bar.h
@interface Bar : Foo

// Bar.m
- (instancetype) initWithResult:(NSTextCheckingResult *)result forLine:(NSString *)line {
  if ( self = [super initWithResult:result forLine:line] ) {
    // do some other stuff
  }
  
  return self;
}


// BarTest.m
- (void)setUp
{
  [super setUp];
  Bar * bar = [Bar parse:line]; // this causes the warning
}