Get PID for bundle identifier

pid_for_bundle.m

// gcc pid_for_bundle.m -o pid_for_bundle -framework Foundation -framework AppKit
#import <Foundation/Foundation.h>
#import <AppKit/AppKit.h>

int main(int argc, const char **argv) {
    if (argc != 2) {
        printf("missing bundle identifier\n");
        printf("usage: %s com.example.name\n", argv[0]);
        exit(-1);
    }
    const char *identifier = argv[1];
    NSString *appIdentifier = [[NSString alloc] initWithBytes:identifier length:strlen(identifier) encoding:NSASCIIStringEncoding];
    NSArray<NSRunningApplication *> *runningApps = [NSRunningApplication runningApplicationsWithBundleIdentifier:appIdentifier];
    if (runningApps == nil || [runningApps count] == 0) {
        printf("no running apps identified with %s identifier\n", identifier);
        exit(-1);
    }
    NSRunningApplication *app = runningApps[0];
    pid_t pid = [app processIdentifier];
    printf("pid for %s is %d\n", identifier, pid);
    return 0;
}