NSArray @property由NSMutableArray支持 [英] NSArray @property backed by a NSMutableArray

问题描述

我已经定义了一个类，我希望公共属性看起来像是由 NSArray 支持。这很简单，但在我的情况下，实际的支持ivar是 NSMutableArray ：

I've defined a class where I'd like a public property to appear as though it is backed by an NSArray. That is simple enough, but in my case the actual backing ivar is an NSMutableArray:

@interface Foo
{
    NSMutableArray* array;
}
@property (nonatomic, retain) NSArray* array;

@end

在我的实施文件中（ * .m ）我 @synthesize 该属性但我立即遇到警告，因为使用 self.words 与尝试修改 NSArray 相同。

In my implementation file (*.m) I @synthesize the property but I immediately run into warnings because using self.words is the same as trying to modifying an NSArray.

执行此操作的正确方法是什么？

What is the correct way to do this?

谢谢！

推荐答案

我会声明 readonly NSArray 在您的标头中并覆盖该数组的getter以返回私有 NSMutableArray的副本在您的实现中声明。请考虑以下事项。

I would declare a readonly NSArray in your header and override the getter for that array to return a copy of a private NSMutableArray declared in your implementation. Consider the following.

Foo.h

@interface Foo

@property (nonatomic, retain, readonly) NSArray *array;

@end

Foo.m

@interface Foo ()

@property (nonatomic, retain) NSMutableArray *mutableArray

@end

#pragma mark -

@implementation Foo

@synthesize mutableArray;

- (NSArray *)array
{
    return [[self.mutableArray copy] autorelease];
}

@end

这篇关于NSArray @property由NSMutableArray支持的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！