blocks|key|290391|text|您只需使用NSFetchRequest请求现有对象，更改需要更新的任何字段(只需一个简单的myObject.propertyName设置器)，然后在数据上下文上执行保存操作。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|BOLD|entityRanges|data|290392|编辑以添加代码示例。我同意MCannon的观点，核心数据绝对值得一读。|290393|此代码假设您使用包含核心数据内容的模板创建了项目，例如您的应用程序委托具有托管对象上下文等。请注意，这里没有错误检查，这只是基本代码。|290394|获取对象的|290395|//+Retrieve+the+context
if+(managedObjectContext+==+nil)+{
++++managedObjectContext+=+[(YourAppNameAppDelegate+*)[[UIApplication+sharedApplication]+delegate]+managedObjectContext];
}

//+Retrieve+the+entity+from+the+local+store+--+much+like+a+table+in+a+database
NSEntityDescription+*entity+=+[NSEntityDescription+entityForName:@"YourEntityName"+inManagedObjectContext:managedObjectContext];
NSFetchRequest+*request+=+[[NSFetchRequest+alloc]+init];
[request+setEntity:entity];

//+Set+the+predicate+--+much+like+a+WHERE+statement+in+a+SQL+database
NSPredicate+*predicate+=+[NSPredicate+predicateWithFormat:@"YourIdentifyingObjectProperty+==+%25@",+yourIdentifyingQualifier];
[request+setPredicate:predicate];

//+Set+the+sorting+--+mandatory,+even+if+you're+fetching+a+single+record/object
NSSortDescriptor+*sortDescriptor+=+[[NSSortDescriptor+alloc]+initWithKey:@"yourIdentifyingQualifier"+ascending:YES];
NSArray+*sortDescriptors+=+[[NSArray+alloc]+initWithObjects:sortDescriptor,+nil];
[request+setSortDescriptors:sortDescriptors];
[sortDescriptors+release];+sortDescriptors+=+nil;
[sortDescriptor+release];+sortDescriptor+=+nil;

//+Request+the+data+--+NOTE,+this+assumes+only+one+match,+that+
//+yourIdentifyingQualifier+is+unique.+It+just+grabs+the+first+object+in+the+array.+
YourEntityName+*thisYourEntityName+=+[[managedObjectContext+executeFetchRequest:request+error:&error]+objectAtIndex:0];
[request+release];+request+=+nil;|code-block|syntax|javascript|290396|更新对象|290397|thisYourEntityName.ExampleNSStringAttributeName+=+@"The+new+value";
thisYourEntityName.ExampleNSDateAttributeName+=+[NSDate+date];|290398|保存更改|290399|NSError+*error;
[self.managedObjectContext+save:&error];|290400|现在，您的对象/行已更新。|290401|entityMap^0|5|E|2A|2|0|0|2|0|0|0|0|0|4|0|0|0|4|0|0|0|D|0^^$0|@$1|2|3|4|5|6|7|13|8|@$9|14|A|15|B|C]|$9|16|A|17|B|D]]|E|@]|F|$]]|$1|G|3|H|5|6|7|18|8|@$9|19|A|1A|B|D]]|E|@]|F|$]]|$1|I|3|J|5|6|7|1B|8|@]|E|@]|F|$]]|$1|K|3|L|5|6|7|1C|8|@]|E|@]|F|$]]|$1|M|3|N|5|O|7|1D|8|@]|E|@]|F|$P|Q]]|$1|R|3|S|5|6|7|1E|8|@$9|1F|A|1G|B|D]]|E|@]|F|$]]|$1|T|3|U|5|O|7|1H|8|@]|E|@]|F|$P|Q]]|$1|V|3|W|5|6|7|1I|8|@$9|1J|A|1K|B|D]]|E|@]|F|$]]|$1|X|3|Y|5|O|7|1L|8|@]|E|@]|F|$P|Q]]|$1|Z|3|10|5|6|7|1M|8|@$9|1N|A|1O|B|D]]|E|@]|F|$]]|$1|11|3|-4|5|6|7|1P|8|@]|E|@]|F|$]]]|12|$]]

You simply request the existing object using an <code>NSFetchRequest</code>, change whatever fields need to be updated (a simple myObject.propertyName setter is all that's required), and then perform a save action on the data context.

EDIT to add code example. I agree with MCannon, Core Data is definitely worth reading up about.

This code assumes you created the project with a template that includes Core Data stuff, such that your app delegate has a managed object context, etc. Note that there is NO error checking here, this is just basic code.

Fetching the object 

<pre><code>// Retrieve the context
if (managedObjectContext == nil) {
 managedObjectContext = [(YourAppNameAppDelegate *)[[UIApplication sharedApplication] delegate] managedObjectContext];
}

// Retrieve the entity from the local store -- much like a table in a database
NSEntityDescription *entity = [NSEntityDescription entityForName:@"YourEntityName" inManagedObjectContext:managedObjectContext];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entity];

// Set the predicate -- much like a WHERE statement in a SQL database
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"YourIdentifyingObjectProperty == %@", yourIdentifyingQualifier];
[request setPredicate:predicate];

// Set the sorting -- mandatory, even if you're fetching a single record/object
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"yourIdentifyingQualifier" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[sortDescriptors release]; sortDescriptors = nil;
[sortDescriptor release]; sortDescriptor = nil;

// Request the data -- NOTE, this assumes only one match, that 
// yourIdentifyingQualifier is unique. It just grabs the first object in the array. 
YourEntityName *thisYourEntityName = [[managedObjectContext executeFetchRequest:request error:&amp;error] objectAtIndex:0];
[request release]; request = nil;
</code></pre>

Update the object

<pre><code>thisYourEntityName.ExampleNSStringAttributeName = @"The new value";
thisYourEntityName.ExampleNSDateAttributeName = [NSDate date];
</code></pre>

Save the change

<pre><code>NSError *error;
[self.managedObjectContext save:&amp;error];
</code></pre>

Now your object/row is updated.

blocks|key|3007936|text|http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreData/Articles/cdFetching.html将向您展示如何获取实体，|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3007937|http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdUsingMOs.html将向您展示如何更改属性并保存它们。|3007938|核心数据是你真正想要阅读大量苹果文档并熟悉它的地方，从长远来看，它将为你节省几个小时。希望这能有所帮助！|3007939|entityMap|0|LINK|mutability|MUTABLE|url|http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreData/Articles/cdFetching.html|1|http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdUsingMOs.html^0|0|2V|0|0|0|2W|1|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@]|9|@$A|S|B|T|1|U]]|C|$]]|$1|D|3|E|5|6|7|V|8|@]|9|@$A|W|B|X|1|Y]]|C|$]]|$1|F|3|G|5|6|7|Z|8|@]|9|@]|C|$]]|$1|H|3|-4|5|6|7|10|8|@]|9|@]|C|$]]]|I|$J|$5|K|L|M|C|$N|O]]|P|$5|K|L|M|C|$N|Q]]]]

<a href="http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreData/Articles/cdFetching.html" rel="nofollow">http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreData/Articles/cdFetching.html</a> will show you how to fetch an entity, 

<a href="http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdUsingMOs.html" rel="nofollow">http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdUsingMOs.html</a> will show you how to change properties, and save them. 

core data is something where you really want to read a lot of the apple documentation and become familiar, it will save you hours in the long run. hope this helps!

I am playing around with a new project, a split view iPad app using Core Data, and I was wondering, as its fairly clear how to add and remove an item. If I was to say alter this to hold text, then that text be shown in a <code>UITextView</code>, how can I edit or overwrite an object in CoreData?

So the user types their note in the <code>UITextView</code> and when they leave that it edits and saves the note (object in the table view) they have currently selected.

Appreciate any help thanks.

CoreData Edit/Overwrite Object

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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