Objective-C中的BOOL问题 [英] BOOL issue in Objective-C

问题描述

当我试图从字典中获取BOOL时，我得到:

When I'm trying to do this to get the BOOL from a dictionary, I get:

BOOL isTrue = [someDict objectForKey: @"isTrue"];

我得到:

Initialization makes integer from pointer without a cast

我这样做是为了设置字典:

I set the dictionary by doing this:

self.someDict = [[NSMutableDictionary alloc]
    initWithObjectsAndKeys:
        self.isTrue, @"isTrue",
        nil];

有什么想法吗?

推荐答案

使用:

BOOL isTrue = [[someDict objectForKey:@"isTrue"] boolValue];

将BOOL存储在NSDictionary中的唯一方法是将其包装在NSNumber对象中. BOOL是原始的，字典仅包含对象.

The only way to store a BOOL in an NSDictionary is to box it in an NSNumber object. A BOOL is primitive, and a dictionary only holds objects.

类似地，要在字典中存储BOOL，请使用:

Similarly, to store a BOOL in a dictionary, use:

[someDict setObject:[NSNumber numberWithBool:isTrue] forKey:@"isTrue"];

(回应评论)

有两种方法可以将其表示为@property.一种是将ivar声明为BOOL，另一种是将其声明为NSNumber.

There are two ways of representing this as an @property. One is to declare the ivar as a BOOL, and the other is to declare it as an NSNumber.

对于第一种情况，其ivar为:BOOL isTrue;，而属性为@property BOOL isTrue;(显然，我忽略了命名约定).

For the first case, the ivar is: BOOL isTrue;, and the property is @property BOOL isTrue; (I'm ignoring naming conventions, obviously).

对于NSNumber，其ivar为:NSNumber * isTrue;，而属性为@property (nonatomic, retain) NSNumber * isTrue;.如果采用这种方法，则可能需要提供第二种设置方法(setIsTrueBool或其他方法)，该方法可以让您只传入YES或NO，然后自己进行装箱.否则，任何打电话给它的人都必须自己做拳击.

For the NSNumber, the ivar is: NSNumber * isTrue; and the property is @property (nonatomic, retain) NSNumber * isTrue;. If you go with this route, you might want to provide a second setter method (setIsTrueBool or something) that allows you to just pass in YES or NO, and then you do the boxing yourself. Otherwise anyone who calls this would have to do the boxing themselves.

我个人最有可能选择选项#1，但这实际上取决于课程的目的.

I'd personally most likely go with option #1, but it really depends on what the class's purpose was.

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