Question

在以下代码中：

//anArray is a Array of Dictionary with 5 objs. 

//here we init with the first
NSMutableDictionary *anMutableDict = [[NSMutableDictionary alloc] initWithDictionary:[anArray objectAtIndex:0]];

... use of anMutableDict ...
//then want to clear the MutableDict and assign the other dicts that was in the array of dicts

for (int i=1;i<5;i++) {
    [anMutableDict removeAllObjects];
    [anMutableDict initWithDictionary:[anArray objectAtIndex:i]];
}

为什么这次崩溃？如何清除一个nsmutabledict并分配一个新的dict？

谢谢你的家伙。

马科斯。

Answer 1

你永远不会“重新启动”物体。初始化旨在用于新alloc ed实例，并且可能在初始化完成后进行假设。在NSMutableDictionary的情况下，您可以使用setDictionary:用新词典或addEntriesFromDictionary:完全替换字典的内容，以添加来自另一个字典的条目（除非有除去当前条目冲突）。

更一般地说，您可以释放该字典并在数组中生成mutableCopy字典。

Answer 2

如果您使用自动释放的字典，您的代码将更加简单：

NSMutableDictionary *anMutableDict = [NSMutableDictionary dictionaryWithDictionary:[anArray objectAtIndex:0]];

... use of anMutableDict ...

for (int i=1; i<5; i++)
{
    anMutableDict = [NSMutableDictionary dictionaryWithDictionary:[anArray objectAtIndex:i]];
}

但是我没有看到你最后那个循环的重点。

Answer 3

这不是你使用init / alloc的方式。相反，尝试：

//anArray is a Array of Dictionary with 5 objs. 

//here we init with the first
NSMutableDictionary *anMutableDict = [[NSMutableDictionary alloc] initWithDictionary:[anArray objectAtIndex:0]];

... use of anMutableDict ...
//then want to clear the MutableDict and assign the other dicts that was in the array of dicts

for (int i=1;i<5;i++) {
    [anMutableDict removeAllObjects];
    [anMutableDict addEntriesFromDictionary:[anArray objectAtIndex:i]];
}

NSMutableDictionary，alloc，init和reiniting

3 个答案: