我正在尝试使用 NSCoding 从我的应用程序中保存一些值。我能够保存该值但无法检索它。

这是我声明协议(protocol)的地方:

@interface AddReminderEventViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource, NSCoding> 

这是我遵守协议(protocol)的地方:

-(void)encodeWithCoder:(NSCoder *)enCoder
{
[enCoder encodeObject:self.eventRepeatDurationDate   forKey:kEventRepeatDuration];
[enCoder encodeObject:self.eventIDsMutableArray      forKey:kEventIDsMutableArray];
[enCoder encodeObject:self.eventRepeatDurationString forKey:@"mytest"];}

这里:

-(id)initWithCoder:(NSCoder *)decoder {

if (self = [super init]){

    self.eventRepeatDurationDate = [[decoder decodeObjectForKey:kEventRepeatDuration]  retain];
    self.eventIDsMutableArray    = [[decoder decodeObjectForKey:kEventIDsMutableArray] retain];
    self.eventRepeatDurationString = [[decoder decodeObjectForKey:@"mytest"]  retain];} return self; }

这里是我调用方法进行归档和取消归档的地方:

    [self saveDataToDisk];
    [self loadDataFromDisk];

下面是这些方法的主体和它的 NSLog 内容:

- (void)saveDataToDisk {
NSString *reminderEventIDsPathString = @"~/Library/Application Support/ReminderIDs.archive";    
//reminderEventIDsPathString = @"~/Library/Application Support/ReminderIDs.archive";
reminderEventIDsPathString = [reminderEventIDsPathString stringByExpandingTildeInPath];
NSLog(@"WATCH1: reminderEventIDsPathString is %@", reminderEventIDsPathString);

NSMutableDictionary *rootObject;
rootObject = [NSMutableDictionary dictionary];

[rootObject setValue:eventRepeatDurationString forKey:@"mytest"];
NSLog(@"1rootObject IS %@", rootObject);

[NSKeyedArchiver archiveRootObject:rootObject toFile:reminderEventIDsPathString];}

reminderEventIDsPathString is /Users/tester/Library/Application Support/iPhone Simulator/5.0/Applications/E26D57DE-C4E1-4318-AEDD-7207F41010A9/Library/Application Support/ReminderIDs.archive
2012-01-16 15:47:48.578 [29658:15503] 1rootObject IS {mytest = 7;}

下面是解档代码及其 NSLog 内容:

- (void)loadDataFromDisk {
NSString *testValue = [[NSString alloc] init];
NSString *reminderEventIDsPathString = @"~/Library/Application Support/ReminderIDs.archive";    
reminderEventIDsPathString = [reminderEventIDsPathString stringByExpandingTildeInPath];
NSLog(@"WATCH2: reminderEventIDsPathString is %@", reminderEventIDsPathString);

NSMutableDictionary *rootObject;
rootObject = [[NSKeyedUnarchiver unarchiveObjectWithFile:reminderEventIDsPathString] retain];

NSLog(@"2rootObject IS %@", rootObject);

NSLog(@"WATCH3 - %@", [rootObject objectForKey:@"mytest" ]);

if ([rootObject valueForKey:@"mytest"]) {
    testValue = [rootObject valueForKey:@"mytest"];
    NSLog(@"WATCH: testValue is %@", testValue); } }

2012-01-16 15:48:14.965 [29658:15503] WATCH2: reminderEventIDsPathString is /Users/tester/Library/Application Support/iPhone Simulator/5.0/Applications/E26D57DE-C4E1-4318-AEDD-7207F41010A9/Library/Application Support/ReminderIDs.archive

2012-01-16 15:48:17.879 [29658:15503] 2rootObject IS (null)

我错过了什么，我无法取消存档内容？我只是专注于我的编码器/解码器方法中最简单的值，只是为了测试它，但我什至无法让字符串值起作用。

谢谢

最佳答案

您保存和加载提醒的路径错误。也许替换成这个

NSString *reminderEventIDsPathString = [[NSHomeDirectory() stringByAppendingPathComponent:@"Documents"] stringByAppendingPathComponent:@"ReminderIDs.archive"];

关于ios - NSCoding NSKeyedUnarchiver unarchiveObjectWithFile : returning null，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/8887116/