objective-c - 如何在 View 中保存 UIImage

Question

在我的应用程序中，我有两个 View :一个 mapView 和一个详细 View 。 mapView 有注释，注释 View 有正确的标注按钮，当按下标注按钮时，这些按钮会将详细 View 推送到堆栈上。在详细 View 中，用户可以拍摄显示在详细 View Controller 上的 UIImage 上的照片。我想要的是在每个注释的细节 View Controller 上显示不同的图像。我读到我可以使用单例，我也做了一个单例类，但我不知道如何使用它。有人可以帮我吗？这是一些代码:

我的 MKAnnotation 类:

#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

这是详细 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

您肯定有一个实现 MKAnnotation 协议(protocol)的类。

在这个类中只需添加一个 UIImage 属性并为每个注释分配其自定义图像。

然后在呈现详细 View 时，您只需传递注释并访问您定义的图像属性。

编辑在您的 PinViewController 中，只需像这样声明一个属性

@property(nonatomic, strong) MapPoint * annotation;

在你展示你的PinViewController之前，给它分配相应的注解，做一些类似的事情

detailedController.annotation = theAnnotation;

做任何你需要做的事情来获取图像，然后以这种方式将其存储在注释中

self.annotation.image = theImage;

现在注释正在存储图像，因此只要您将其保存在内存中，它就可以供您使用。

下次推送详细 View 时，您可以检查该注释是否已经有图像

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