[NSDictionary getObjects:andKeys:] 的示例

发布于 2024-09-02 15:00:29 字数 1275 浏览 3 评论 0原文

我找不到方法 [NSDictionary getObjects:andKeys:] 的工作示例。我能找到的唯一示例，没有编译。我在这里提供了错误/警告，以防有人正在搜索它们。

我感到困惑的原因是 NSDictionary 上的大多数方法都返回一个 NSArray。但是，在文档它指出此方法的输出变量以 C 数组形式返回。

以下是如果您按照链接示例操作可能会收到的错误消息/警告：

NSDictionary *myDictionary = ...;

id objects[]; // Error: Array size missing in 'objects'
id keys[]; // Error: Array size missing in 'keys'

[myDictionary getObjects:&objects andKeys:&keys];

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
}

。

NSDictionary *myDictionary = ...;

NSInteger count = [myDictionary count];
id objects[count];
id keys[count];
[myDictionary getObjects:&objects andKeys:&keys]; // Warning: Passing argument 1 of 'getObjects:andKeys:' from incompatible pointer type.

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
}

我将提供一个可行的解决方案作为这个问题的答案。

原文

I couldn't find a working example of the method [NSDictionary getObjects:andKeys:]. The only example I could find, doesn't compile. I provided the errors/warnings here in case someone is searching for them.

The reason I was confused is because most methods on NSDictionary return an NSArray. However, in the documentation it states that the out variables of this method are returned as C arrays.

Here are the error messages/warnings you might get if you follow the linked example:

NSDictionary *myDictionary = ...;

id objects[]; // Error: Array size missing in 'objects'
id keys[]; // Error: Array size missing in 'keys'

[myDictionary getObjects:&objects andKeys:&keys];

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
}

NSDictionary *myDictionary = ...;

NSInteger count = [myDictionary count];
id objects[count];
id keys[count];
[myDictionary getObjects:&objects andKeys:&keys]; // Warning: Passing argument 1 of 'getObjects:andKeys:' from incompatible pointer type.

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
}

I'll provide a working solution as an answer to this question.

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筱武穆 2024-09-09 15:00:29

以下是使用此方法的正确方法：

NSDictionary *myDictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"1", @"A", @"2", @"B", nil];

NSInteger count = [myDictionary count];
id objects[count];
id keys[count];
[myDictionary getObjects:objects andKeys:keys];

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
  NSLog(@"%@ -> %@", obj, key);
}

Here's the correct way to use this method:

NSDictionary *myDictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"1", @"A", @"2", @"B", nil];

NSInteger count = [myDictionary count];
id objects[count];
id keys[count];
[myDictionary getObjects:objects andKeys:keys];

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
  NSLog(@"%@ -> %@", obj, key);
}

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桃扇骨 2024-09-09 15:00:29

在 ARC 下，解决方案需要修改如下（__unsafe_unretained 添加到数组定义中）：

NSDictionary *myDictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"1", @"A", @"2", @"B", nil];

NSInteger count = [myDictionary count];
id __unsafe_unretained objects[count];
id __unsafe_unretained keys[count];
[myDictionary getObjects:objects andKeys:keys];

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
  NSLog(@"%@ -> %@", obj, key);
}

Under ARC the solution needs to be modified as follows (__unsafe_unretained added to the array definitions):

NSDictionary *myDictionary = [NSDictionary dictionaryWithObjectsAndKeys:@"1", @"A", @"2", @"B", nil];

NSInteger count = [myDictionary count];
id __unsafe_unretained objects[count];
id __unsafe_unretained keys[count];
[myDictionary getObjects:objects andKeys:keys];

for (int i = 0; i < count; i++) {
  id obj = objects[i];
  id key = keys[i];
  NSLog(@"%@ -> %@", obj, key);
}

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