NSKeyedUnarchiver unarchiveObjectWithFile：在init：方法中返回nil [英] NSKeyedUnarchiver unarchiveObjectWithFile: returns nil in init: method

问题描述

更新：这个工作，如果我调用archiveRootObject：从applicationDidFinishLaunching：。如果我从一个singleton类的init：方法调用它，它返回nil。

Update: This works if I call archiveRootObject: from applicationDidFinishLaunching:. If I call it from the init: method of a singleton class, it returns nil.

我非常困惑的NSKeyedUnarchiver unarchiveObjectWithFile：的行为。 文档说如果文件不存在，它将返回nil。使用我的对象之一，会发生以下情况：

I'm very confused by the behavior of NSKeyedUnarchiver unarchiveObjectWithFile:. The documentation says that it will return nil if the file doesn't exist. With one of my objects, the following happens:

Game *g1 = [Game getGame];
NSString *archivePath = [Game getArchivePath];
bool success = [NSKeyedArchiver archiveRootObject:g1 toFile:archivePath];
Game *g2 = [NSKeyedUnarchiver unarchiveObjectWithFile:archivePath];

// success is true, g2 is nil

文件实际上确实存在并且正在被archiveRootObject：方法写入。

I've verified that the file actually does exist and is getting written to by the archiveRootObject: method. What am I doing wrong preventing me from getting a Game object back out of the archive?

推荐答案

我遇到了同样的麻烦在Xcode 4.1中与ARC支持：

I've meet the same trouble in Xcode 4.1 with ARC support:

BOOL isFileExist = [[NSFileManager defaultManager] fileExistsAtPath:filePath];
NSAssert(isFileExist, @"filePath does not exist");
NSKeyedUnarchiver* coder =
    [NSKeyedUnarchiver unarchiveObjectWithFile:filePath]; // nil
NSData* data = [[NSFileManager defaultManager] contentsAtPath:filePath];
coder = [NSKeyedUnarchiver unarchiveObjectWithData:data]; // nil
coder = [[NSKeyedUnarchiver alloc] initForReadingWithData:data]; // OK!!!

这似乎是可可触摸的错误。

It seems to be a bug in cocoa-touch.

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