Question

In my app I have two views: a mapView, and a detail view. The mapView has annotations, and the annotation views have right callout buttons that push the detail view onto the stack when the callout button is pressed. In the detail view, the user can take a picture that appears on the UIImage that is on the detail view controller. What I want is for a different image to be on the detail view controller for each annotation. I have read that I can use a singleton, and I have made a singleton class, but I do not know how to use it. Can someone help me out?
Here is some code:

My MKAnnotation class:

#import <CoreLocation/CoreLocation.h>
#import <MapKit/MapKit.h>

@interface MapPoint : NSObject <MKAnnotation>
{
    NSString *_address;
    CLLocationCoordinate2D _coordinate;
    NSNumber *_identifier;
    UIImage *_image;
}

- (id)initWithAddress:(NSString*)address
    coordinate:(CLLocationCoordinate2D)coordinate
         title:(NSString *)t
    identifier:(NSNumber *)ident;


//This is a required property from MKAnnotation
@property (nonatomic, readonly) CLLocationCoordinate2D coordinate;

//This is an optional property from MKAnnotataion
@property (nonatomic, copy) NSString *title;
@property (nonatomic, readonly, copy) NSString *subtitle;
@property (nonatomic) BOOL animatesDrop;
@property (nonatomic) BOOL canShowCallout;

@property (copy) NSString *address;
@property (copy) NSNumber *identifier;
@property (copy,nonatomic) UIImage *image;

@end

@implementation MapPoint

@synthesize title, subtitle, animatesDrop, canShowCallout;
@synthesize address = _address, coordinate = _coordinate, identifier = _identifier, image = _image;

-(id)initWithAddress:(NSString *)address
   coordinate:(CLLocationCoordinate2D)coordinate
        title:(NSString *)t
   identifier:(NSNumber *)ident
{
    self = [super init];

    if (self) {
        _address = [address copy];
        _coordinate = coordinate;
        _identifier = ident;

        [self setTitle:t];

        NSDate *theDate = [NSDate date];

        subtitle = [NSDateFormatter localizedStringFromDate:theDate
                                              dateStyle:NSDateFormatterMediumStyle
                                              timeStyle:NSDateFormatterMediumStyle];
    }
    return self;
}

@end

Here is the detail view controller:

#import <UIKit/UIKit.h>
@class P2OViewController;

@interface PinViewController : UIViewController <UINavigationControllerDelegate, UIImagePickerControllerDelegate,UITextFieldDelegate>

{
    __weak IBOutlet UILabel *label;
    __weak IBOutlet UIButton *removeButton;
    NSString *addressForLabel;
    __weak P2OViewController *_vc;
    __weak NSNumber *_identifier;
}

@property (weak, nonatomic) IBOutlet UIImageView *imageView;
@property (weak, nonatomic) IBOutlet UILabel *label;
@property (weak, nonatomic) IBOutlet UIButton *removeButton;
@property (weak, nonatomic) P2OViewController *vc;
@property (weak, nonatomic) NSNumber *identifier;

-(void)takePicture:(id)sender;

-(void)buttonPressed:(id)sender;

@end

#import "PinViewController.h"
#import "MapPoint.h"
#import "P2OViewController.h"

@implementation PinViewController

@synthesize imageView, label, removeButton;
@synthesize vc = _vc, identifier = _identifier;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        UIBarButtonItem *pic = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemCamera
                                                                        target:self
                                                                        action:@selector(takePicture:)];
    [[self navigationItem]setRightBarButtonItem:pic];

}
return self;
}

-(void)takePicture:(id)sender
    {
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc]init];

    //If our device has a camera, we ant to take a picture, otherwise, we just pick from photo library
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
        [imagePicker setSourceType:UIImagePickerControllerSourceTypeCamera];
    } else {
        [imagePicker setSourceType:UIImagePickerControllerSourceTypePhotoLibrary];
    }
    [imagePicker setDelegate:self];

    //Place the image picker on the screen
    [self presentViewController:imagePicker
                   animated:YES
                 completion:nil];
}

-(void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    //Get picked image from info dictionary
    UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];

    //Put the image onto the screen in out image view
    [imageView setImage:image];

    //Take image picker off the screen - you must call this dismiss method
    [self dismissViewControllerAnimated:YES
                         completion:nil];

}

@end

Answer 1

You surely have a class implementing the MKAnnotation protocol.

In this class simply add a UIImage property and assign to every annotation its custom image.

Then when presenting the detailed view you just pass around the annotation and access its image property you defined.

EDIT
In your PinViewController simply declare a property like this

@property(nonatomic, strong) MapPoint * annotation;

Before you present your PinViewController assign the corresponding annotation to it, doing something like

detailedController.annotation = theAnnotation;

Do whatever you need to do to get the image, then store it in the annotation in this way

self.annotation.image = theImage;

Now the annotation is storing the image, so as long as you keep it in memory it will be there available for you.

The next time you push the detailed view you can perform a check to see whether that annotation has already an image or not

if(nil != self.annotation.image) {
     // do something
} else {
     // do something else
}