Question

我有一个自定义对象，一个UIImageView子类，它有几个gestureRecognizer个对象。

如果我在NSMutableArray中存储了许多这些对象，那么如何将这个对象数组保存到磁盘中，以便在用户再次运行应用程序时加载它？

我想从磁盘加载数组并使用这些对象。

Answer 1

我对类似内容的实现如下并且完美运行：

自定义对象（设置）应实现协议NSCoding：

-(void)encodeWithCoder:(NSCoder *)encoder{
    [encoder encodeObject:self.difficulty forKey:@"difficulty"];
    [encoder encodeObject:self.language forKey:@"language"];
    [encoder encodeObject:self.category forKey:@"category"];
    [encoder encodeObject:self.playerType forKey:@"playerType"];
}

- (id)initWithCoder:(NSCoder *)decoder {
    if (self = [super init]) {
        self.difficulty = [decoder decodeObjectForKey:@"difficulty"];
        self.language = [decoder decodeObjectForKey:@"language"];
        self.category = [decoder decodeObjectForKey:@"category"];
        self.playerType = [decoder decodeObjectForKey:@"playerType"];
    }
    return self;
}

以下代码将自定义对象写入文件（set.txt），然后将其还原到数组myArray：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *appFile = [documentsDirectory stringByAppendingPathComponent:@"set.txt"];

NSMutableArray *myObject=[NSMutableArray array];
[myObject addObject:self.settings];    

[NSKeyedArchiver archiveRootObject:myObject toFile:appFile]; 

NSMutableArray* myArray = [NSKeyedUnarchiver unarchiveObjectWithFile:appFile];

Answer 2

//store the array
[NSKeyedArchiver archiveRootObject:myArray toFile:@"someFile"];

//load the array
NSMutableArray* myArray = [NSKeyedUnarchiver unarchiveObjectWithFile:@"someFile"];

Official References

请注意，当数组包含自定义对象类型时，必须确保您的类型符合NSCoding Protocol之前的效果。

Answer 3

此博客文章介绍了如何使用NSKeyedArchiver将一系列自定义对象存储到磁盘，并使用NSKeyedUnarchiver将其读回：

http://www.cocoabuilder.com/archive/cocoa/240775-saving-nsarray-of-custom-objects.html

Apple也有一个非常有用的指南，Archives and Serializations Programming Guide。

Answer 4

如果有人需要，我想与Kostas解决方案分享我的改进。

类名可用于生成存储对象的文本文件名。
在viewWillDisappear方法中保存视图控制器的对象并在viewDidLoad方法中恢复它们是一个很好的解决方案。
文件名应以单独的方法生成，以避免重复的代码。
恢复对象后，应检查它是否为零。

- (void)viewDidLoad
{
  [super viewDidLoad];

  // Restoring form object from the file
  NSString *formFilePath = [self formFilePath];
  RRCreateResumeForm *form = [NSKeyedUnarchiver unarchiveObjectWithFile:formFilePath];
  if (form != nil) {
    self.formController.form = form;
  }
}


- (void)viewWillDisappear:(BOOL)animated
{
  [super viewWillDisappear:animated];

  // Saving the form object to the file
  NSString *formFilePath = [self formFilePath];
  [NSKeyedArchiver archiveRootObject:self.formController.form toFile:formFilePath];
}


// Returns a file path to the file with stored form data for form controller
- (NSString *)formFilePath
{
  NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
  NSString *documentsDirectory = [paths objectAtIndex:0];
  NSString *formClassName = NSStringFromClass( [self.formController.form class] );
  NSString *formFileName = [NSString stringWithFormat:@"%@.txt", formClassName];
  NSString *formFilePath = [documentsDirectory stringByAppendingPathComponent:formFileName];

  return formFilePath;
}

在iOS中保存/序列化自定义对象的正确方法

4 个答案: