NSKeyedArchiver archivedDataWithRootObject：

Question

NSKeyedArchiver的参数是archivedDataWithRootObject：应该是我要保存的数组，还是将数组转换为NSData？

Answer 1

Yuji的回答是正确的。但更准确地说，数组的元素必须实现协议并将自己的代码填充到方法initWithCoder：和encodeWithCoder： 像：

- (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"];
}

然后你可以使用archiver和unchariver，如：

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，您可以参考“Archiving Objective-C Objects with NSCoding”。

Answer 2

要将通用数组转换为NSData，您需要一个归档程序！如果您知道如何提供NSData，则知道如何使用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:。