How can I add a boolean value to a NSDictionary?

问题

Well, for integers I would use NSNumber. But YES and NO aren't objects, I guess. A.f.a.i.k. I can only add objects to an NSDictionary, right?

I couldn't find any wrapper class for booleans. Is there any?

回答1:

You use NSNumber.

It has init... and number... methods that take booleans, just as it does integers and so on.

From the NSNumber class reference:

// Creates and returns an NSNumber object containing a 
// given value, treating it as a BOOL.
+ (NSNumber *)numberWithBool:(BOOL)value

and:

// Returns an NSNumber object initialized to contain a
// given value, treated as a BOOL.
- (id)initWithBool:(BOOL)value

and:

// Returns the receiver’s value as a BOOL.
- (BOOL)boolValue

回答2:

The new syntax since Apple LLVM Compiler 4.0

dictionary[@"key1"] = @(boolValue);
dictionary[@"key2"] = @YES;

The syntax converts BOOL to NSNumber, which is acceptable to NSDictionary.

回答3:

If you are declaring it as a literal and you are using clang v3.1 or above, you should use @NO / @YES if you are declaring it as a literal. E.g.

NSMutableDictionary* foo = [@{ @"key": @NO } mutableCopy];
foo[@"bar"] = @YES;

For more info on that:

http://clang.llvm.org/docs/ObjectiveCLiterals.html

回答4:

As jcampbell1 pointed out, now you can use literal syntax for NSNumbers:

NSDictionary *data = @{
                      // when you always pass same value
                      @"someKey" : @YES
                      // if you want to pass some boolean variable
                      @"anotherKey" : @(someVariable)
                      };

回答5:

Try this:

NSMutableDictionary *dic = [[NSMutableDictionary alloc] init];
[dic setObject:[NSNumber numberWithBool:TRUE]  forKey:@"Pratik"];
[dic setObject:[NSNumber numberWithBool:FALSE] forKey:@"Sachin"];

if ([dic[@"Pratik"] boolValue])
{
    NSLog(@"Boolean is TRUE for 'Pratik'");
}
else
{
    NSLog(@"Boolean is FALSE for 'Pratik'");
}

if ([dic[@"Sachin"] boolValue])
{
    NSLog(@"Boolean is TRUE for 'Sachin'");
}
else
{
    NSLog(@"Boolean is FALSE for 'Sachin'");
}

The output will be as following:

Boolean is TRUE for 'Pratik'

Boolean is FALSE for 'Sachin'

来源：https://stackoverflow.com/questions/903906/how-can-i-add-a-boolean-value-to-a-nsdictionary

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objective-c

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