blocks|key|444704|text|NSArray不能保证您只能存储给定对象的一个副本，因此您必须确保自己处理该副本(或使用NSOrderedSet)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|444705|也就是说，这里有几种方法。如果您的category对象实现isEqual:来匹配category_title，那么您可以只使用-indexOfObject:。|444706|如果无法做到这一点(因为category对象使用了不同的相等定义)，请使用-indexOfObjectPassingTest:。它需要一个代码块，在这个代码块中，您可以执行任何想要定义“测试”的测试-在本例中，测试category_title字符串相等性。|444707|请注意，这些都是为NSArray声明的，因此如果只查看NSMutableArray头文件/文档，您将看不到它们。|444708|编辑:代码示例。这假设类CASCategory的对象具有NSString属性categoryTitle+(我不能让自己在ivar名称中加上下划线:-)：|444709|++++CASCategory+*cat1+=+[[CASCategory+alloc]+init];
++++[cat1+setCategoryTitle:@"foo"];
++++CASCategory+*cat2+=+[[CASCategory+alloc]+init];
++++[cat2+setCategoryTitle:@"bar"];
++++CASCategory+*cat3+=+[[CASCategory+alloc]+init];
++++[cat3+setCategoryTitle:@"baz"];

++++NSMutableArray+*array+=+[NSMutableArray+arrayWithObjects:cat1,+cat2,+cat3,+nil];
++++[cat1+release];
++++[cat2+release];
++++[cat3+release];

++++NSUInteger+barIndex+=+[array+indexOfObjectPassingTest:%5EBOOL(id+obj,+NSUInteger+idx,+BOOL+*stop)+{
++++++++if+([[(CASCategory+*)obj+categoryTitle]+isEqualToString:@"bar"])+{
++++++++++++*stop+=+YES;
++++++++++++return+YES;
++++++++}
++++++++return+NO;
++++}];

++++if+(barIndex+!=+NSNotFound)+{
++++++++NSLog(@"The+title+of+category+at+index+%25lu+is+%25@",+barIndex,+[[array+objectAtIndex:barIndex]+categoryTitle]);
++++}
++++else+{
++++++++NSLog(@"Not+found");
++++}|code-block|syntax|javascript|444710|entityMap^0|0|7|18|C|0|T|8|1R|F|0|11|Q|2Z|E|0|9|7|R|E|0|C|B|S|8|12|D|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|19|8|@$9|1A|A|1B|B|C]|$9|1C|A|1D|B|C]]|D|@]|E|$]]|$1|L|3|M|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]|$9|1J|A|1K|B|C]]|D|@]|E|$]]|$1|N|3|O|5|P|7|1L|8|@]|D|@]|E|$Q|R]]|$1|S|3|-4|5|6|7|1M|8|@]|D|@]|E|$]]]|T|$]]

<code>NSArray</code> does not guarantee that you can only store one copy of a given object, so you have to make sure that you handle that yourself (or use <code>NSOrderedSet</code>).

That said, there are a couple approaches here. If your category objects implement <code>isEqual:</code> to match category_title, then you can just use <code>-indexOfObject:</code>.

If you can't do that (because the category objects use a different definition of equality), use <code>-indexOfObjectPassingTest:</code>. It takes a block in which you can do whatever test you want to define your "test" - in this case, testing <code>category_title</code> string equality.

Note that these are all declared for <code>NSArray</code>, so you won't see them if you are only looking at the <code>NSMutableArray</code> header/documentation.

EDIT: Code sample. This assumes objects of class <code>CASCategory</code> with an <code>NSString</code> property <code>categoryTitle</code> (I can't bring myself to put underscores in an ivar name :-):

<pre><code> CASCategory *cat1 = [[CASCategory alloc] init];
 [cat1 setCategoryTitle:@"foo"];
 CASCategory *cat2 = [[CASCategory alloc] init];
 [cat2 setCategoryTitle:@"bar"];
 CASCategory *cat3 = [[CASCategory alloc] init];
 [cat3 setCategoryTitle:@"baz"];

 NSMutableArray *array = [NSMutableArray arrayWithObjects:cat1, cat2, cat3, nil];
 [cat1 release];
 [cat2 release];
 [cat3 release];

 NSUInteger barIndex = [array indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
 if ([[(CASCategory *)obj categoryTitle] isEqualToString:@"bar"]) {
 *stop = YES;
 return YES;
 }
 return NO;
 }];

 if (barIndex != NSNotFound) {
 NSLog(@"The title of category at index %lu is %@", barIndex, [[array objectAtIndex:barIndex] categoryTitle]);
 }
 else {
 NSLog(@"Not found");
 }
</code></pre>

blocks|key|659183|text|我不确定我是否理解了这个问题，但类似这样的东西可能会起作用(假设可变数组包含“Category”类的对象)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|659184|int+indx;
bool+chk;
for+(Category+*aCategory+in+theArray)+
{
++++chk+=+([[aCategory+category_title]+isEqualToString:@"valOfCategoryTitle"])
++++if+(+chk+)
++++++++indx+=+[theArray+indexOfObject:aCategory];
}|code-block|syntax|javascript|659185|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Not sure that I understand the question but something like this might work (assuming the Mutable Array contains objects of Class "Category"):

<pre><code>int indx;
bool chk;
for (Category *aCategory in theArray) 
{
 chk = ([[aCategory category_title] isEqualToString:@"valOfCategoryTitle"])
 if ( chk )
 indx = [theArray indexOfObject:aCategory];
}
</code></pre>

blocks|key|444827|text|尝试下面的代码要简单得多：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|444828|int+f+=+[yourArray+indexOfObject:@"yourString"];|code-block|syntax|javascript|444829|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this code much more simpler:-

<pre><code>int f = [yourArray indexOfObject:@"yourString"];
</code></pre>

I want to get the index of an object within the NSMutableArray of categories. 

The category object has an attribute "category_title" and I want to be able to get the index by passing the value of category_title. 

I have looked through the docs and can't find a simple way to go about this.

How do I get the index of an object in an NSArray using string value?

我想要在类别的NSMutableArray中获得一个对象的索引。category对象有一个属性" category_title“，我希望能够通过传递category_title的值来获得索引。我已经看过文档了，找不到一种简单的方法来解决这个问题。

问如何使用字符串值获取NSArray中对象的索引？
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