CSS not displaying when using WKURLSchemeHandler on iOS 17+ with Xcode 15.3+

I’m encountering an issue with CSS not displaying when using WKURLSchemeHandler to load local HTML files.

•	When I package the app using Xcode 15.3 or above, the CSS styles do not display on iOS 17 or higher. However, on iOS 16.7.1, the CSS displays correctly.
•	If I use Xcode 15.2 to package the app, the CSS loads and displays correctly on all iOS versions.

I am using WKURLSchemeHandler to intercept and load the local HTML files. Is there any known issue or workaround for this?

You can now post this in the “Safari & Web” section of the Apple Developer forums for further assistance!

//
//  CustomURLSchemeHandler.m
//  HTMLTest
//
//  Created by lvxue on 2024/9/23.
//

// CustomURLSchemeHandler.m
#import "CustomURLSchemeHandler.h"

@implementation CustomURLSchemeHandler

// 拦截请求并提供本地 HTML 文件
- (void)webView:(WKWebView *)webView startURLSchemeTask:(id<WKURLSchemeTask>)urlSchemeTask {
    NSURL *url = urlSchemeTask.request.URL;
    //NSString *filePath;
    // 获取本地 HTML 文件路径
    NSString *filePath = [[NSBundle mainBundle] pathForResource:@"index" ofType:@"html" inDirectory:@"LoaclHtml.bundle/A4"];
    // 判断请求的是 HTML、CSS 或其他文件
    if ([url.lastPathComponent hasSuffix:@".css"]) {
        filePath = [[NSBundle mainBundle] pathForResource:@"style" ofType:@"css" inDirectory:@"LoaclHtml.bundle/A4/css"];
    } else if ([url.lastPathComponent hasSuffix:@".js"]) {
        filePath = [[NSBundle mainBundle] pathForResource:@"yourJSFileName" ofType:@"js" inDirectory:@"LoaclHtml.bundle/A4/js"];
    } // 可以继续添加其他资源类型如图片

    
    NSData *htmlData = [NSData dataWithContentsOfFile:filePath];
    NSString *mimeType = [self mimeTypeForPath:filePath];

    // 创建响应头
    NSURLResponse *response = [[NSURLResponse alloc] initWithURL:url
                                                       MIMEType:mimeType
                                          expectedContentLength:htmlData.length
                                               textEncodingName:@"utf-8"];
    
    // 提供响应数据
    [urlSchemeTask didReceiveResponse:response];
    [urlSchemeTask didReceiveData:htmlData];
    [urlSchemeTask didFinish];
}

// 停止请求
- (void)webView:(WKWebView *)webView stopURLSchemeTask:(id<WKURLSchemeTask>)urlSchemeTask {
    // 通常不需要处理停止请求的逻辑
}

- (NSString *)mimeTypeForPath:(NSString *)path {
    NSString *fileExtension = [path pathExtension];
    
    if ([fileExtension isEqualToString:@"html"]) {
        return @"text/html";
    } else if ([fileExtension isEqualToString:@"css"]) {
        return @"text/css";
    } else if ([fileExtension isEqualToString:@"js"]) {
        return @"application/javascript";
    } else if ([fileExtension isEqualToString:@"png"]) {
        return @"image/png";
    } else if ([fileExtension isEqualToString:@"jpg"] || [fileExtension isEqualToString:@"jpeg"]) {
        return @"image/jpeg";
    } else if ([fileExtension isEqualToString:@"gif"]) {
        return @"image/gif";
    }
    
    return @"application/octet-stream";
}

@end
code-block