Xcode Call a function from another .h file to update it's status

Question

I have two UIView and link to the following files
1. FirstViewController.h and .m
2. MapTypeOption.h and .m

FirstViewController is link to MapTypeOption with Navigation control

I would like to perform the following task
Use a UI Segment Control at MapTypeOption to change
the Google map type in FirstViewController

so in FirstViewController.h I have a function as follow

- (void)ChangeMapType:(int )SelectIndex

my FirstViewController.m has a function as follow

-(void)ChangeMapType:(int )SelectIndex
{
    switch (SelectIndex) 
    {
    case 0:
        MainMapView.mapType = MKMapTypeStandard;
        break;
    case 1:
        MainMapView.mapType = MKMapTypeSatellite;
        break;
    case 2:
        MainMapView.mapType = MKMapTypeHybrid;
        break;

    default:
        MainMapView.mapType = MKMapTypeStandard;
        break;
    }
}

in MapTypeOption.m I have the following

#import "FirstViewController.h"
@class FirstViewController;
....
- (IBAction)updatemaptype:(id)sender 
{
    FirstViewController *newFirstViewControllerobj=[[FirstViewController alloc] init];
    [newFirstViewControllerobj ChangeMapType:MapTypeSegment.selectedSegmentIndex];
}    

I can compile and run my program (with simulator) but even I select a different
segment at MapTypeOption view nothing is changed in FirstViewController

Answer 1

您可能需要在ChangeMapType中调用[view setNeedsDisplay]来导致视图更新。