在NSUserDefaults（NSString）中保存日期不起作用 [英] Saving a date in NSUserDefaults (as NSString) not working

问题描述

我正在将此日期保存在NSUSerDefaults中：

  2011-04-14T13：18：25 + 0000 
  

但是我不想要最后一位（+0000），所以我用这个方法把它关掉：

  NSString * since = [last objectForKey：@updated_time]; 
 NSString * cutOff = @+ 0000; 
 NSRange range = [since rangeOfString：cutOff]; 
 self.lastUpdated = [since substringToIndex：range.location]; 
 [[NSUserDefaults standardUserDefaults] setObject：lastUpdated forKey：@lastUpdated]; 
  

正如你所看到的，这只是一个非常简单的操作，将上述字符串剪切为： / p>

  2011-04-14T13：18：25 
  

然而，当我从NSUserDefaults加载它时，我得到：

  2011-04 -14 13:18:25 +0000 
  

任何人都可以告诉我为什么？

更新：

我曾经在.h中像以前一样宣布了lastUpdated：

  @interface TwitModel 
 {
 NSString * lastUpdated; 
} 
 
 @property（retain）NSString * lastUpdated; 
  

in .m：

  @synthesize lastUpdated; 
  

当我想加载它：

  if（self.lastUpdated == nil）{
 self.lastUpdated = [[NSUserDefaults standardUserDefaults] objectForKey：@lastUpdated]; 
} 
  

解决方案

您需要调用code>同步在 NSUserDefaults 中，以便正确保存数据：

  [[NSUserDefaults standardUserDefaults] synchronize]; 
  

---

编辑 p>

这是我的工作代码：

  //输出以前的发布的存储值
 NSLog（@从先前启动的值：％@，[[NSUserDefaults standardUserDefaults] valueForKey：@lastUpdated]）; 
 
 NSString * since = @2011-04-14T13：18：25 + 0000; 
 NSLog（@Since：％@，since）; 
 NSString * cutOff = @+ 0000; 
 NSRange range = [since rangeOfString：cutOff]; 
 NSString * lastUpdated = [since substringToIndex：range.location]; 
 [[NSUserDefaults standardUserDefaults] setObject：lastUpdated forKey：@lastUpdated]; 
 [[NSUserDefaults standardUserDefaults] synchronize]; 
 
 NSLog（@Value：％@，[[NSUserDefaults standardUserDefaults] valueForKey：@lastUpdated]）; 
  

输出：

  2011-04-14 08：52：29.972 TestApp [2117：207]从上次发布的价值：2011-04-14T13：18：25 
 2011-04-14 08:52： 29.973 TestApp [2117：207]自：2011-04-14T13：18：25 + 0000 
 2011-04-14 08：52：29.975 TestApp [2117：207]价值：2011-04-14T13：18： 25 
  

I'm trying to save this date in NSUSerDefaults:

2011-04-14T13:18:25+0000

But I don't want the last bit (+0000), so I chopped it off using this method:

NSString *since = [last objectForKey:@"updated_time"];
NSString *cutOff = @"+0000"; 
NSRange range = [since rangeOfString:cutOff];
self.lastUpdated = [since substringToIndex:range.location];
[[NSUserDefaults standardUserDefaults] setObject:lastUpdated forKey:@"lastUpdated"];

As you can see, it's just a very simple operation that will chop the above string to this:

2011-04-14T13:18:25

However when I load this from NSUserDefaults, I get this:

2011-04-14 13:18:25 +0000

Can anyone tell me why?

UPDATE:

I declared lastUpdated as usual in .h:

@interface TwitModel
{
    NSString *lastUpdated;
}

@property (retain) NSString *lastUpdated;

in .m:

@synthesize lastUpdated;

When I want to load it:

    if(self.lastUpdated == nil) {
        self.lastUpdated = [[NSUserDefaults standardUserDefaults] objectForKey:@"lastUpdated"];
    }

解决方案

You need to call synchronize on NSUserDefaults in order for it to properly save the data:

[[NSUserDefaults standardUserDefaults] synchronize];

---

EDIT

Here's my working code:

// Output previous launch's stored value
NSLog(@"Value From Previous Launch: %@", [[NSUserDefaults standardUserDefaults] valueForKey:@"lastUpdated"]);

NSString *since = @"2011-04-14T13:18:25+0000";
NSLog(@"Since: %@", since);
NSString *cutOff = @"+0000"; 
NSRange range = [since rangeOfString:cutOff];
NSString* lastUpdated = [since substringToIndex:range.location];
[[NSUserDefaults standardUserDefaults] setObject:lastUpdated forKey:@"lastUpdated"];
[[NSUserDefaults standardUserDefaults] synchronize];

NSLog(@"Value: %@", [[NSUserDefaults standardUserDefaults] valueForKey:@"lastUpdated"]);

And the output:

2011-04-14 08:52:29.972 TestApp[2117:207] Value From Previous Launch: 2011-04-14T13:18:25
2011-04-14 08:52:29.973 TestApp[2117:207] Since: 2011-04-14T13:18:25+0000
2011-04-14 08:52:29.975 TestApp[2117:207] Value: 2011-04-14T13:18:25

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