利用runtime获取工程内的所有类

【记个代码】不包含系统类
第一个版本有几个问题：

1. objc_copyClassNamesForImage的返回值未free
2. 未做严格的判空

// 获取工程里的所有类
- (NSArray *)getResourceClassNames {
    NSArray *(^block)(const char *) = ^(const char *imageName) {
        unsigned int classCount;
        const char **classes = objc_copyClassNamesForImage(imageName, &classCount);
        NSMutableArray *arr = nil;
        if (classes && classCount) {
	        arr = [NSMutableArray arrayWithCapacity:classCount];
            for (int i = 0; i < classCount; i++) {
            	const char *name = classes[i];
            	NSString *clsName = [NSString stringWithCString:name encoding:NSUTF8StringEncoding];
            	[arr addObject:clsName];
        	}
        	free(classes);	// runtime中包含copy的方法都需要手动free
        }
        return arr.copy;
    };
    
    NSString *bundleName = [[NSBundle mainBundle] objectForInfoDictionaryKey:@"CFBundleName"];
    
    unsigned int imageCount = 0;
    const char **imageList = objc_copyImageNames(&imageCount);
    
    NSUInteger totalCount = 0;
    // image : classes names，先存dic，说不定有啥用
    NSMutableDictionary *dic = [NSMutableDictionary dictionaryWithCapacity:64];
    
    if (imageList && imageCount) {
        for (int i = 0; i < imageCount; i++) {
            NSString *img = [NSString stringWithCString:imageList[i] encoding:NSUTF8StringEncoding];
            if ([img rangeOfString:bundleName].location != NSNotFound) {
                NSArray *arr = block(imageList[i]);
                if (arr) {
                 	dic[img] = arr;
 	             	totalCount += arr.count;
                }
            }
        }
        free(imageList);
    }

    NSMutableArray *arr = [NSMutableArray arrayWithCapacity:totalCount];
    [dic enumerateKeysAndObjectsUsingBlock:^(id  _Nonnull key, NSArray *_Nonnull obj, BOOL * _Nonnull stop) {
        [arr addObjectsFromArray:obj];
    }];
    
    return arr.copy;
}