需要澄清 addObjectsFromArray 函数
我有以下代码（items 和 itemsCopy 都是 NSMutableArray 的）：
//DO: populate items w/ 30 elements
[self.itemsCopy addObjectsFromArray:self.items];
//DO: remove all elements in items
结果
Begin Pass 1:
itemsCopy = 0
items = 30
End Pass 1:
itemsCopy = 30
items = 0
Begin Pass 2:
itemsCopy = 0
items = 30
End Pass 2:
itemsCopy = 30
items = 0
如何不断地将项目附加到 itemsCopy 的末尾？我希望场景是这样的：
Begin Pass 1:
itemsCopy = 0
items = 30
End Pass 1:
itemsCopy = 30;
items = 0;
Begin Pass 2:
itemsCopy = 30
items = 30
End Pass 2:
itemsCopy = 60
items = 0
I have the following code (both items and itemsCopy are NSMutableArray's):
//DO: populate items w/ 30 elements
[self.itemsCopy addObjectsFromArray:self.items];
//DO: remove all elements in items
Results
Begin Pass 1:
itemsCopy = 0
items = 30
End Pass 1:
itemsCopy = 30
items = 0
Begin Pass 2:
itemsCopy = 0
items = 30
End Pass 2:
itemsCopy = 30
items = 0
How can I constantly append items to the end of itemsCopy? I would like the scenario to look like this:
Begin Pass 1:
itemsCopy = 0
items = 30
End Pass 1:
itemsCopy = 30;
items = 0;
Begin Pass 2:
itemsCopy = 30
items = 30
End Pass 2:
itemsCopy = 60
items = 0
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评论（1）
通过保留刚刚填充
itemsCopy属性的相同数组。无论您使用什么方法，它显然都会被重置为空数组。By keeping the same array you just filled in the
itemsCopyproperty. It's clearly being reset to an empty array with whatever method you're using.