NSMutableString * ms = [[NSMutableString alloc] initWithString:@"中华人民共和国"];
        if (CFStringTransform((__bridge CFMutableStringRef)ms, 0, kCFStringTransformMandarinLatin, NO)) {
            NSLog(@"pinyin: %@", ms);
        }//有声调
        if (CFStringTransform((__bridge CFMutableStringRef)ms, 0, kCFStringTransformStripDiacritics, NO)) {
            NSLog(@"pinyin: %@", ms);
        }//无声调

使用苹果提供的汉字转拼音方法