如何在“for（项目中的id项目）”objective-c循环中获取数组索引？

How can I get the array index within a "for (id item in items)" loop in objective-c? For NSArray or NSMutableArray for example.

如何在objective-c中的“for（id item in items）”循环中获取数组索引？例如，对于NSArray或NSMutableArray。

For example:

例如：

for (id item in items) {
    // How to get item's array index here

}

2 个解决方案

#1

Only way I can think of is:

我能想到的唯一方法是：

NSUInteger count = 0;
for (id item in items)
{
    //do stuff using count as your index
    count++;
}

---

Bad Way

Alternatively, you can use the indexOfObject: message of a NSArray to get the index:

或者，您可以使用NSArray的indexOfObject：消息来获取索引：

NSUInteger index;
for (id item in items)
{
    index = [items indexOfObject:item];
    //do stuff using index
}

#2

Alternatively, you can use -enumerateObjectsUsingBlock:, which passes both the array element and the corresponding index as arguments to the block:

或者，您可以使用-enumerateObjectsUsingBlock :,它将数组元素和相应的索引作为参数传递给块：

[items enumerateObjectsUsingBlock:^(id item, NSUInteger idx, BOOL *stop)
{
    …
}];

Bonus: concurrent execution of the block operation on the array elements:

额外：在数组元素上并发执行块操作：

[items enumerateObjectsWithOptions:NSEnumerationConcurrent
    usingBlock:^(id item, NSUInteger idx, BOOL *stop)
{
    …
}];