NSKeyedArchiver archivedDataWithRootObject：

Question

NSKeyedArchiver archivedDataWithRootObject:的参数应该是我试图保存的数组，还是转换为NSData的数组？

Answer 1

要将泛型数组转换为NSData，您需要一个归档程序！如果您知道如何提供NSData，那么您就知道如何使用NSKeyedArchiver。所以：

NSArray* array= ... ;
NSData* data=[NSKeyedArchiver archivedDataWithRootObject:array];

当然，array中的所有元素都需要实现encodeWithCoder:。

Answer 2

Yuji的答案是正确的。但更准确地说，数组元素必须实现协议，并将自己的代码填充到initWithCoder:和encodeWithCoder: like方法中：

- (id)initWithCoder:(NSCoder *)decoder {
    if (self = [super init]) {
        self.title = [decoder decodeObjectForKey:@"title"];
        self.author = [decoder decodeObjectForKey:@"author"];
        self.published = [decoder decodeBoolForKey:@"published"];
    }
    return self;
}
- (void)encodeWithCoder:(NSCoder *)encoder {
    [encoder encodeObject:title forKey:@"time"];
    [encoder encodeObject:author forKey:@"author"];
    [encoder encodeBool:published forKey:@"published"];
}

然后，您可以使用归档程序和解压程序，如下所示：

NSData *data = [NSKeyedArchiver archivedDataWithRootObject:notes];
[[NSUserDefaults standardUserDefaults] setObject:data forKey:@"notes"];

NSData *notesData = [[NSUserDefaults standardUserDefaults] objectForKey:@"notes"];
NSArray *notes = [NSKeyedUnarchiver unarchiveObjectWithData:notesData];

更多信息，你可以参考"Archiving Objective-C Objects with NSCoding“。