Question

我对Objective-C很新，并且有一些初学者问题。我有一个应用程序，其区域应该有点像照片库。用户从相机胶卷中选择一张照片，照片将显示在UIImageViews中。我正在尝试保存他们选择的图像。我有9个UIImageView，问题是当我为每个UIImageView选择不同的照片，关闭并重新启动应用程序时，其他8个UIImageViews会显示存储在第一个图像视图中的照片。这是我正在使用的代码：

- (NSString *)dataFilePath {
    NSArray *paths = NSSearchPathForDirectoriesInDomains(
                                                         NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    return [documentsDirectory stringByAppendingPathComponent:kFilename9];
}

- (void)applicationDidEnterBackground:(UIApplication*)application {
    NSLog(@"Image on didenterbackground: %@", imageView);
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView2.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView3.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView4.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView5.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView6.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView7.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView8.image)];
    self.imageData = [NSData dataWithData:UIImagePNGRepresentation(imageView9.image)];

    [self.imageData writeToFile:[self dataFilePath] atomically:YES];
    NSLog(@"The image is: %@", [[imageView image] description]);
    NSLog(@"dataFilePath is: %@", [self dataFilePath]);

}

- (void)viewDidLoad
{

    NSString *filePath = [self dataFilePath];
    NSLog(@"FilePath: %@", filePath);
    NSLog(@"Image: %@", imageView);
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
        NSData *vdlData = [[NSData alloc] initWithContentsOfFile:filePath];
        imageView.image = [[UIImage alloc] initWithData:vdlData];
        imageView2.image = [[UIImage alloc] initWithData:vdlData];
        imageView3.image = [[UIImage alloc] initWithData:vdlData];
        imageView4.image = [[UIImage alloc] initWithData:vdlData];
        imageView5.image = [[UIImage alloc] initWithData:vdlData];
        imageView6.image = [[UIImage alloc] initWithData:vdlData];
        imageView7.image = [[UIImage alloc] initWithData:vdlData];
        imageView8.image = [[UIImage alloc] initWithData:vdlData];
        imageView9.image = [[UIImage alloc] initWithData:vdlData];
    }


    UIApplication *app = [UIApplication sharedApplication];
    [[NSNotificationCenter defaultCenter] addObserver:self
                                             selector:@selector(applicationDidEnterBackground:)
                                                 name:UIApplicationDidEnterBackgroundNotification
                                               object:app];

    [super viewDidLoad];

}

我正在试图弄清楚我需要改变什么才能让UIImageViews显示正确的图片，而不是全部显示相同的图片。这可能是一个简单的修复，但是非常感谢任何帮助，谢谢！

Answer 1

在我开始使用解决方案之前，我必须警告你，你这样做的方式并不正确。我建议你从头开始学习iOS开发。 Apple自己的文档是一个非常好的开始。 http://developer.apple.com/library/ios/#documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/Introduction/Introduction.html

现在，回到你的问题。你在这里做的只是保存一个图像，而不是全部9个图像。您始终为处理的每个图像设置self.imageData，并覆盖其先前的值，只将最后一个图像保存到文件中。

因此，为了使您的代码正常工作，您必须为每个图像视图使用imageData对象，然后将该数据对象写入文件。

在您的情况下，最好通过使用循环来优化代码，而不是使用多个对象（例如imageView，imageView2，...）。

另外，请确保照顾好自己的记忆。例如imageView.image已分配但尚未发布。

Answer 2

好的，我会这样做：

使用NSUserDefaults将图像保存为可变数组：

<强> ViewController.h

@property(retain) NSUserDefaults *user;

<强> ViewController.m

@synthesize user;

- (void)viewWillAppear:(BOOL)animated
{

    self.user = [NSUserDefaults standardUserDefaults];

修改

NSMutableArray* array = [[self.user objectForKey:@"images"]mutableCopy]; while(array == nil) { [self.user setObject:[NSMutableArray arrayWithObject:@""] forKey:@"images"] array = [[self.user objectForKey:@"images"]mutableCopy]; NSLog(@"%@",@"attempting to create an array to store the images in"); }

结束修改 }

- (void)applicationDidEnterBackground:(UIApplication*)application { NSLog(@"Image on didenterbackground: %@", imageView); NSMutableArray* array = [NSMutableArray arrayWithObject:[NSData dataWithData:UIImagePNGRepresentation(imageView.image)]]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView2.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView3.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView4.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView5.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView6.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView7.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView8.image)]; [array addObject:[NSData dataWithData:UIImagePNGRepresentation(imageView9.image)]; [self.user setObject:array forKey:@"images"]; } - (void)viewDidLoad { NSMutableArray* array = [[self.user objectForKey:@"images"]mutableCopy];

修改

if(array.count == 9) { imageView.image = [[UIImage alloc] initWithData:[array objectAtIndex:0]]; imageView2.image = [[UIImage alloc] initWithData:[array objectAtIndex:1]]; imageView3.image = [[UIImage alloc] initWithData:[array objectAtIndex:2]]; imageView4.image = [[UIImage alloc] initWithData:[array objectAtIndex:3]]; imageView5.image = [[UIImage alloc] initWithData:[array objectAtIndex:4]]; imageView6.image = [[UIImage alloc] initWithData:[array objectAtIndex:5]]; imageView7.image = [[UIImage alloc] initWithData:[array objectAtIndex:6]]; imageView8.image = [[UIImage alloc] initWithData:[array objectAtIndex:7]]; imageView9.image = [[UIImage alloc] initWithData:[array objectAtIndex:8]]; }

结束编辑

UIApplication *app = [UIApplication sharedApplication]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:app]; [super viewDidLoad]; } - (void)viewDidUnload { self.user = nil; }

这样，您就不会丢失图像或数据，它们将被存储并轻松访问，即使您更新应用程序也不会消失。

干杯！

Answer 3

好吧，我看到两个问题。首先，在viewDidLoad中，所有图像都获得initWithData：vdlData ...所以它们都获得了相同的数据。这就是为什么他们都是一样的。

此外，当您尝试保存它们时，在...didEnterBackground中，您一遍又一遍地覆盖imageData的值...当您保存它时，它只是最后一个你已分配给imageData。您可能想要创建一个NSArray，并将它们存储在那里，将它们从viewDidLoad中的数组中拉出来。

iOS：问题保存照片

3 个答案: