注意，在Swift中，你可以这样做

let testBool: Bool = true
NSLog("testBool = %@", testBool.description)

这将记录testBool = true

%d, 0为假，1为真。

BOOL b; 
NSLog(@"Bool value: %d",b);

or

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

基于数据类型%@的变化如下

For Strings you use %@
For int  you use %i
For float and double you use %f

你可以这样做:

BOOL flag = NO;
NSLog(flag ? @"YES" : @"NO");

布尔值只是整数，它们只是类型转换的值，比如……

typedef signed char     BOOL; 

#define YES (BOOL)1
#define NO (BOOL)0

BOOL value = YES; 
NSLog(@"Bool value: %d",value);

如果输出为1，则为YES，否则为NO

我们可以用四种方法检查

第一种方法是

BOOL flagWayOne = TRUE; 
NSLog(@"The flagWayOne result is - %@",flagWayOne ? @"TRUE":@"FALSE");

第二种方法是

BOOL flagWayTwo = YES; 
NSLog(@"The flagWayTwo result is - %@",flagWayTwo ? @"YES":@"NO");

第三种方法是

BOOL flagWayThree = 1;
NSLog(@"The flagWayThree result is - %d",flagWayThree ? 1:0);

第四种方法是

BOOL flagWayFour = FALSE; // You can set YES or NO here.Because TRUE = YES,FALSE = NO and also 1 is equal to YES,TRUE and 0 is equal to FALSE,NO whatever you want set here.
NSLog(@"The flagWayFour result is - %s",flagWayFour ? YES:NO);

//assuming b is BOOL. ternary operator helps us in any language.
NSLog(@"result is :%@",((b==YES)?@"YES":@"NO"));