修改main.m文件内代码
1.在@interface CUICatalog : NSObject下添加
-(id)initWithURL:(NSURL *)URL error:(NSError **)error;方法

2.修改
void exportCarFileAtPath(NSString * carPath, NSString *outputDirectoryPath) 方法：

void exportCarFileAtPath(NSString * carPath, NSString *outputDirectoryPath)
{
NSError *error = nil;

outputDirectoryPath = [outputDirectoryPath stringByExpandingTildeInPath];

//之前代码
// CUIThemeFacet *facet = [CUIThemeFacet themeWithContentsOfURL:[NSURL fileURLWithPath:carPath] error:&error];
//
// CUICatalog catalog = [[CUICatalog alloc] init];
//
// / Override CUICatalog to point to a file rather than a bundle */
// [catalog setValue:facet forKey:@"_storageRef"];
// 替换成以下代码
CUICatalog catalog = nil;
if ([CUICatalog instancesRespondToSelector:@selector(initWithURL:error:)]) {
/ If CUICatalog has the URL API (Mojave), use it. */
catalog = [[CUICatalog alloc] initWithURL:[NSURL fileURLWithPath:carPath] error:&error];
} else {
CUIThemeFacet facet = [CUIThemeFacet themeWithContentsOfURL:[NSURL fileURLWithPath:carPath] error:&error];
catalog = [[CUICatalog alloc] init];
/ Override CUICatalog to point to a file rather than a bundle /
[catalog setValue:facet forKey:@"_storageRef"];
}
NSCAssert(!error, @"Error attempting to open asset catalog (%@): %@", carPath, error);
/ CUICommonAssetStorage won't link */
CUICommonAssetStorage *storage = [[NSClassFromString(@"CUICommonAssetStorage") alloc] initWithPath:carPath];

for (NSString *key in [storage allRenditionNames])
{
    printf("%s\n", [key UTF8String]);
    
    NSArray* pathComponents = [key pathComponents];
    if (pathComponents.count > 1)
    {
        // Create subdirectories for namespaced assets (those with names like "some/namespace/image-name")
        NSArray* subdirectoryComponents = [pathComponents subarrayWithRange:NSMakeRange(0, pathComponents.count - 1)];
        
        NSString* subdirectoryPath = [outputDirectoryPath copy];
        for (NSString* pathComponent in subdirectoryComponents)
        {
            subdirectoryPath = [subdirectoryPath stringByAppendingPathComponent:pathComponent];
        }
        
        [[NSFileManager defaultManager] createDirectoryAtPath:subdirectoryPath
                                  withIntermediateDirectories:YES
                                                   attributes:nil
                                                        error:&error];
    }
    
    NSMutableArray *images = getImagesArray(catalog, key);
    for( CUINamedImage *image in images )
    {
        if( CGSizeEqualToSize(image.size, CGSizeZero) )
            printf("\tnil image?\n");
        else
        {
            CGImageRef cgImage = [image image];
            NSString *idiomSuffix = idiomSuffixForCoreThemeIdiom(image.idiom);
            
            NSString *sizeClassSuffix = @"";
            
            if (image.sizeClassHorizontal || image.sizeClassVertical)
            {
                sizeClassSuffix = [NSString stringWithFormat:@"-%@x%@", sizeClassSuffixForSizeClass(image.sizeClassHorizontal), sizeClassSuffixForSizeClass(image.sizeClassVertical)];
            }
            
            NSString *scale = image.scale > 1.0 ? [NSString stringWithFormat:@"@%dx", (int)floor(image.scale)] : @"";
            NSString *name = [NSString stringWithFormat:@"%@%@%@%@.png", key, idiomSuffix, sizeClassSuffix, scale];
            printf("\t%s\n", [name UTF8String]);
            if( outputDirectoryPath )
                CGImageWriteToFile(cgImage, [outputDirectoryPath stringByAppendingPathComponent:name]);
        }
    }
}

}