Unless its another typo, you have an extra colon in xour code right after sender:
-(IBAction)NrofQuestChange:(UIStepper *)sender:{
double value = [sender value];
[NrOfQuestLabel setText: [NSString stringWithFormat:@"%d", (int)value]];
}
should be
-(IBAction)NrofQuestChange:(UIStepper *)sender{
double value = [sender value];
[NrOfQuestLabel setText: [NSString stringWithFormat:@"%d", (int)value]];
}
Thats why the compiler can't decide whether sender is a variable or part of the method name.