Objective-C formatting string for boolean?

Question

What formatter is used for boolean values?

EDIT:

Example: NSLog(@\" ??\", BOOL_VAL);, what is ?? ?

Answer 1

I created a category of NSString with this

+ (instancetype)stringWithBool:(BOOL)boolValue {
return boolValue ? @"YES" : @"NO";
}

And use it like this:

[NSString stringWithBool:boolValue];

Answer 2

Add this inline function to your .h file:

static inline NSString* NSStringFromBOOL(BOOL aBool) {
    return aBool? @"YES" : @"NO";
}

Now you are ready to go...

NSLog(@"%@", NSStringFromBOOL(BOOL_VAL));

Answer 3

In Objective-C, the BOOL type is just a signed char. From <objc/objc.h>:

typedef signed char BOOL;
#define YES         (BOOL)1
#define NO          (BOOL)0

So you can print them using the %d formatter But that will only print a 1 or a 0, not YES or NO.

Or you can just use a string, as suggested in other answers.

Answer 4

Format strings for use with NSLog and [NSString stringWithFormat] are documented here:

http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html

BOOL/bool/boolean are not even mentioned...

Answer 5

One way to do it is to convert to strings (since there are only two possibilities, it isn't hard):

NSLog(@" %s", BOOL_VAL ? "true" : "false");

I don't think there is a format specifier for boolean values.

Answer 6

I would recommend

NSLog(@"%@", boolValue ? @"YES" : @"NO");

because, um, BOOLs are called YES or NO in Objective-C.