QuietLog, and a little demonstration

log.m

#import <Foundation/Foundation.h>

// clang -fobjc-arc -Wall -Wformat -Weverything -Wno-format-nonliteral -framework Foundation -o log log.m

// Compiler likes explicit function prototypes prior to first use.
// Add an attribute to get additional checking from the compiler
extern void QuietLog (NSString *format, ...) __attribute__((format(__NSString__, 1, 2)));

// !!! The attribute above isn't warning like it should, but NSLog's _is_ working.
// This is NSLog's attribute.  I'm currently baffled.
// extern void NSLog(NSString *format, ...) __attribute__((format(__NSString__, 1, 2)));

void QuietLog (NSString *format, ...) {
    va_list argList;

    va_start (argList, format);
    NSString *message = [[NSString alloc] initWithFormat: format
                                          arguments: argList]; // autorelease if not ARC
    va_end (argList);

    fprintf (stderr, "%s\n", [message UTF8String]);

} // QuietLog


int main (void) {
    @autoreleasepool {
        NSArray *array = [NSArray arrayWithObjects: @"Greeble", @"Bork", @"Fnord", nil];
        NSLog (@"The array is %@", array);
        QuietLog (@"The array is %@", array);

        // Force some warnings.  These actually don't warn
        NSLog (@"The array is %@", 3.1415);
        QuietLog (@"The array is %@", 3.1415);

        // NSLog gets a warning, but not QuietLog
        NSLog (@"The array is %s", 12);
        QuietLog (@"The array is %s", 12);
    }

    return 0;

} // main