ios - 在数组中查找对象的最佳方法

Question

我有数组，例如：（（对象，对象），（对象，对象，对象，对象））

每个object都有属性.objectID。找到特定对象的最佳方法是objectID什么？

Answer 1

这里有两个选择：

选项 1：使用嵌套的 for 循环

CustomObject *searchingObject;

// searching through the first array (which has arrays inside of it)
// Note: this will stop looping if it searched through all the objects or if it found the object it was looking for
for (int i = 0; i < [firstArray count] && searchingObject; i++) {

    // accessing the custom objects inside the nested arrays
    for (CustomObject *co in firstArray[i]) {

        if ([co.objectId == 9235) {
            // you found your object
            searchingObject = co; // or do whatever you wanted to do.
            // kill the inside for-loop the outside one will be killed when it evaluates your 'searchingObject'
            break;
        }
    }
}

选项 2：使用块：

// you need __block to write to this object inside the block
__block CustomObject *searchingObject;

// enumerating through the first array (containing arrays)
[firstArray enumerateObjectsUsingBlock:^(NSArray *nestedArray, NSUInteger indx, BOOL *firstStop) {

    // enumerating through the nested array
    [nestedArray enumerateObjectsUsingBlock:^(CustomObject *co, NSUInteger nestedIndx, BOOL *secondStop) {

        if ([co.objectId == 28935) {
            searchingObject = co; // or do whatever you wanted to do.
            // you found your object now kill both the blocks
            *firstStop = *secondStop = YES;
        }
    }];
}];

尽管仍考虑 N^2 执行时间，但它们只会在需要时运行。一旦他们找到对象，他们就会停止搜索。

Answer 2

试试看

[ary filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"objectID == %@", objectID]];

--

id object = nil;
NSPredicate *pred = [NSPredicate predicateWithFormat:@"objectID == %@", objectID];    

for(NSArray *subAry in ary)
{
    NSArray *result = [subAry filteredArrayUsingPredicate:pred];
    if(result && result.count > 0)
    {
        object = [result objectAtIndex:0];
        break;
    }
}

因为僵尸关心每个人自己：P

Answer 3

如果您不关心顺序，则可以改为使用以 objectId 为键的字典数组。这使您的搜索 O(N)。