ios - NSManagedObject 的描述显示值,但访问它们显示 NaN?
<p><p>我在这里找到了 <a href="https://stackoverflow.com/a/14036989/92153" rel="noreferrer noopener nofollow">excellent solution</a>用于在迁移模型时创建关系。我在模型本身中遇到了一个奇怪的问题。</p>
<pre><code>-(BOOL)createRelationshipsForDestinationInstance:(NSManagedObject *)dInstance entityMapping:(NSEntityMapping *)mapping manager:(NSMigrationManager *)manager error:(NSError *__autoreleasing *)error
{
NSError *superError = nil;
BOOL ismappingSuccess = ;
if (ismappingSuccess && ){
FTEvent *event = (FTEvent*)dInstance;
NSDate *date = ;
...
</code></pre>
<p><code>event.date_time</code> 这里有一个奇怪的问题,我期待一个值,但在调试器中它显示的值是 <code>(NsTimeInterval) NaN</code> 而不是实际的值(value)。</p>
<p>但是,当我打印事件描述时,我可以清楚地看到提供的日期值。当我执行 <code>event.date_time</code> 时,它怎么可能显示 <code>NaN</code>?</p>
<pre><code>Printing description of event:
<NSManagedObject: 0xbbb9b80> (entity: FTEvent; id: 0xbbbab90 <x-coredata://069BC324-2002-4DBA-879A-DC085C645903/FTEvent/p1> ; data: {
"date_time" = "2014-04-10 23:00:00 +0000";
"is_deleted" = 0;
key = "4F6646FF-4110-427F-B2FD-3CFCAF777793";
notes = Fdsfdsfd;
rating = 1;
record = nil;
timestamp = "2045-04-11 01:19:06 +0000";
})
</code></pre>
<p><strong>FTEvent:</strong></p>
<pre><code>@class FTRecord;
@interface FTEvent : NSManagedObject
{
BOOL is_edited;
}
@property (nonatomic) NSTimeInterval date_time;
@property (nonatomic) BOOL is_deleted;
@property (nonatomic, retain) NSString * key;
@property (nonatomic, retain) NSString * notes;
@property (nonatomic) int16_t rating;
@property (nonatomic) NSTimeInterval timestamp;
@property (nonatomic, retain) FTRecord *record;
</code></pre></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>我刚刚找到它。它可以作为键/值对访问。</p>
<p><strong>错误:</strong></p>
<pre><code>
</code></pre>
<p><strong>正确:</strong></p>
<pre><code>NSDate *date_time = ;
</code></pre>
<p>我错了,它会使用模型上的属性。</p></p>
<p style="font-size: 20px;">关于ios - NSManagedObject 的描述显示值,但访问它们显示 NaN?,我们在Stack Overflow上找到一个类似的问题:
<a href="https://stackoverflow.com/questions/23021817/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/23021817/
</a>
</p>
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