// *** before: ***
// only a constant could be wrapped shortly; a variable or an expression
// needed the full factory call, and the right method had to be chosen
int width = 320;
NSNumber *boxedWidth = [NSNumber numberWithInt:width];

double area = width * 1.5;
NSNumber *boxedArea = [NSNumber numberWithDouble:area];

const char *cName = "Ann";
NSString *name = [NSString stringWithUTF8String:cName];

// *** in version 2012: ***
// @(...) wraps any expression, and the compiler picks the type itself
int width = 320;
NSNumber *boxedWidth = @(width);

double area = width * 1.5;
NSNumber *boxedArea = @(area);

NSNumber *sum = @(width + 20);
NSNumber *isWide = @(width > 300);        // a BOOL comes out

const char *cName = "Ann";
NSString *name = @(cName);                // a C string becomes an NSString

// an enum value is wrapped the same way, which is what puts it in a dictionary
typedef enum { StateIdle, StateBusy } State;
NSDictionary *info = @{@"state": @(StateBusy)};

// ⚠️ @(cName) with a NULL pointer throws; a C string must be checked first