objective-c - 在自定义 getter/setter 方法中使用 NSKeyedArchiver/Unarchiver

Question

我正在尝试使用 NSKeyedArchiver/NSKeyedUnarchiver 将类属性的数据存储在文件中，以便在启动之间保留属性的状态应用程序。

我在 MyClass.h 中声明了属性，如下所示:

@property (nonatomic, weak) NSDictionary *myDictionary;

我在 MyClass.m 中创建了自定义 getter 和 setter 方法，以确保 NSDictionary 写入磁盘:

-(NSDictionary *)myDictionary {
    NSDictionary *dictionary;

    NSString *path = [self pathToDataStore];
    if (![[NSFileManager defaultManager] fileExistsAtPath:path]) {
        dictionary = [NSDictionary dictionary];
    } else {
        NSData *archivedData = [NSData dataWithContentsOfFile:path];
        dictionary = [NSKeyedUnarchiver unarchiveObjectWithData:archivedData];
    }

    return dictionary;
}

-(void)setMyDictionary:(NSDictionary *)dictionary {
    NSString *path = [self pathToDataStore];
    NSDictionary *rootObject = [NSDictionary dictionaryWithDictionary:dictionary];
    [NSKeyedArchiver archiveRootObject:rootObject toFile:path];
    self.myDictionary = dictionary;
}

这导致无限循环调用[self setMyDictionary]，所以显然我做错了什么。但问题出在哪里呢？

Answer 1

而不是:

self.myDictionary = dictionary;

你应该这样做:

@synthesize myDictionary;
...

-(void)setMyDictionary:(NSDictionary *)dictionary {

...
myDictionary = dictionary
}

您的问题发生的原因是调用:

self.myDictionary = dictionary; 

等于

[self setMyDictionary:dictionary];