UIImage 从 UIImagePickerController 获取 nil

Question

我正在尝试更新 Viewcontroller 上的图像，我正在使用 ImagePickerController，我可以看到 chosenImage 有数据，我分配了它。选择图像然后再次加载此 viewcontroller 时，我可以调试以查看它是否命中 loadUserProfile 方法，是的。但是 UIImage 在某处以某种方式变得零。

@property (strong, nonatomic) UIImage *userPicImage;
@property (weak, nonatomic) IBOutlet UIImageView *userProfileImage;

- (void)viewDidLoad {
    [super viewDidLoad];
    [self loadUserProfile];
}

-(void)loadUserProfile
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString * userImageURL = [defaults objectForKey:@"imageURL"];    
    bool isReload = [defaults boolForKey:@"isReload"];

    if(isReload)
    {
         //self.userPicImage is always nil
         [self.userProfileImage setImage:self.userPicImage];
         [defaults setBool:false forKey:@"comingBack"];
         [defaults synchronize];
    }
}

- (void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImagePickerControllerSourceType source = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] ? UIImagePickerControllerSourceTypeCamera : UIImagePickerControllerSourceTypeSavedPhotosAlbum;

    UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
   // userPicImage is not nil here!
    self.userPicImage = chosenImage;

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setBool:true forKey:@"isReload"];
    [defaults synchronize];

    [picker dismissViewControllerAnimated:YES completion:^{        
        if (source == UIImagePickerControllerSourceTypeCamera) {
            [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationNone];
        }
    }];
}

Answer 1

每当 viewdidload 被调用时，viewcontroller 被加载为一个新的 reference，它的所有引用出口和变量都被设置为新的。在您的情况下，userPicImage 是作为新对象启动的，因此从逻辑上讲，其中不会有任何内容。
您最好将图像数据存储在 userdefaults 中并从那里检索。

Answer 2

尝试此代码，因为当您再次加载时 vc 图像数据为零，因此首先将图像数据转换为 base64string。

@property (strong, nonatomic) UIImage *userPicImage;
@property (weak, nonatomic) IBOutlet UIImageView *userProfileImage;

- (void)viewDidLoad {
    [super viewDidLoad];
    [self loadUserProfile];
}

-(void)loadUserProfile
{
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSString * userImageURL = [defaults objectForKey:@"imageURL"];
    bool isReload = [defaults boolForKey:@"isReload"];

    if(isReload)
    {
        //self.userPicImage is always nil
        NSString *base64String=[defaults stringForKey:@"chosenimage"];
        NSData* data = [[NSData alloc] initWithBase64EncodedString:base64String options:0];
        UIImage* image = [UIImage imageWithData:data];
        self.userProfileImage.image=image;
      //  [self.userProfileImage setImage:self.userPicImage];
        [defaults setBool:false forKey:@"comingBack"];
        [defaults synchronize];
    }
}

- (void)imagePickerController:(UIImagePickerController *)picker
didFinishPickingMediaWithInfo:(NSDictionary *)info {
    UIImagePickerControllerSourceType source = [UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera] ? UIImagePickerControllerSourceTypeCamera : UIImagePickerControllerSourceTypeSavedPhotosAlbum;

    UIImage *chosenImage = info[UIImagePickerControllerEditedImage];
    // userPicImage is not nil here!
    self.userPicImage = chosenImage;
    NSData *imageData = UIImageJPEGRepresentation(chosenImage, 1.0);
    NSString *encodedString = [imageData base64Encoding];

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    [defaults setObject:encodedString forKey:@"chosenimage"];
    [defaults setBool:true forKey:@"isReload"];
    [defaults synchronize];

    [picker dismissViewControllerAnimated:YES completion:^{
        if (source == UIImagePickerControllerSourceTypeCamera) {
            [[UIApplication sharedApplication] setStatusBarHidden:YES withAnimation:UIStatusBarAnimationNone];
        }
    }];
}

UIImage 从 UIImagePickerController 获取 nil

UIImage is getting nil from the UIImagePickerController

objective-c

uiimagepickercontroller

uiimage

ios