Xcode 4：提取请求模板变量？ [英] Xcode 4: Fetch Request Template Variables?

问题描述

在Xcode 3.X中，您应该右键点击抓取请求模板的谓词编辑器中的空格，以指定一个变量输入而不是硬编码谓词。

In Xcode 3.X, you were supposed to right-click the whitespace in the fetch request template's predicate editor to specify a variable input rather than a hard-coded predicate.

在XCode 4中这是什么？我拿着选项，右键点击，选项点击等等，不能弄清楚....

Where is this in XCode 4? I've held option, right-clicked, option-clicked, etc and cannot figure it out....

推荐答案

t认为X4有变量了。

I don't think X4 has the variable anymore.

相反，我认为你必须选择一个表达式，然后提供一个 $ VARNAME 形式的变量。

Instead, I think you have to choose an expression and then provide a variable of the form $VARNAME.

例如，给定实体 Alpha ，其属性为 aString ，我创建了一个获取请求模板 bobFetch ，其表达式为 aString == $ TESTVAR 。

For example, given and entity Alpha with an attribute aString, I created a fetch request template bobFetch with an expression of aString == $TESTVAR.

Alpha *a=[NSEntityDescription insertNewObjectForEntityForName:@"Alpha" inManagedObjectContext:self.moc];
a.aString=@"steve";
[self saveContext];
NSDictionary *subVars=[NSDictionary dictionaryWithObject:@"steve" forKey:@"TESTVAR"];
NSFetchRequest *fetchRequest =   [self.managedObjectModel fetchRequestFromTemplateWithName:@"bobRequest" substitutionVariables:subVars];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Alpha" inManagedObjectContext:self.moc];
[fetchRequest setEntity:entity];

如果记录 fetchRequest reports：

If logged fetchRequest reports:

<NSFetchRequest: 0x4d17480> (entity: Alpha; predicate: (aString == "steve"); sortDescriptors: ((null)); type: NSManagedObjectResultType; )

$ b b

...然后可以正常使用。

... and can then be used normally.

NSError *error = nil;
NSArray *fetchedObjects = [self.moc executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
    NSLog(@"fetch error = %@",error);
}
NSLog(@"fetchObjects = %@",fetchedObjects);

图形环境的笨拙的种类，但它工作。

Kind of clumsy for a graphical environment but it works.

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