如何将 NSArray 转换为 NSMutableArray [英] How to convert NSArray to NSMutableArray

问题描述

ABAddressBookRef addressBook = ABAddressBookCreate();
CFArrayRef allPeople = ABAddressBookCopyArrayOfAllPeople(addressBook);  
CFIndex nPeople = ABAddressBookGetPersonCount(addressBook);

NSMutableArray *tempPeoples=[[NSMutableArray alloc]init];

for(int i=0;i<nPeople;i++){

    ABRecordRef i1=CFArrayGetValueAtIndex(allPeople, i);
    [tempPeoples addObject:i1];

//  [peoples addObject:i1];

}// end of the for loop
peoples=[tempPeoples copy];

这段代码给出了异常 b/c 我想将 NSMutableArray 转换为 NSArray请帮忙

This code gives exception b/c I want to convert NSMutableArray to NSArray Please Help

推荐答案

主题内容为如何将 NSArray 转换为 NSMutableArray".要从 NSArray 获取 NSMutableArray，请使用 NSMutableArray +arrayWithArray 上的类方法:.

The subject reads, "How to convert NSArray to NSMutableArray". To get an NSMutableArray from an NSArray, use the class method on NSMutableArray +arrayWithArray:.

您的代码没有显示人民的声明.假设它被声明为 NSMutableArray，如果你试图这样对待它，你可能会遇到问题.当您将复制消息发送到 NSMutableArray 时，您将获得一个不可变对象 NSArray，因此如果您尝试将一个对象添加到复制的 NSMutableArray>，你会得到一个错误.

Your code does not show the declaration for peoples. Assuming it's declared as an NSMutableArray, you can run into problems if you try to treat it as such. When you send the copy message to an NSMutableArray, you get an immutable object, NSArray, so if you try to add an object to a copied NSMutableArray, you will get an error.

CFArrayRef 是免费桥接到 NSArray 的，所以你可以这样简化你的代码:

CFArrayRef is toll free bridged to NSArray, so you could simplify your code this way:

CFArrayRef allPeople = ABAddressBookCopyArrayOfAllPeople(addressBook);
//NSMutableArray *tempPeoples = [NSMutableArray arrayWithArray:(NSArray*)allPeople];
// even better use the NSMutableCopying protocol on NSArray
NSMutableArray *tempPeoples = [(NSArray*)allPeople mutableCopy];
CFRelease(allPeople);
return tempPeoples; // or whatever is appropriate to your code

在上面的代码中 tempPeoples 是一个自动发布的 NSMutableArray 准备好根据需要添加或删除对象.

In the above code tempPeoples is an autoreleased NSMutableArray ready for you to add or remove objects as needed.

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