OC

filePath是沙盒文件路径。我的这个是从其他应用打开分享过来的。
/private/var/mobile/Containers/Data/Application/E8514452-2A92-48D3-9424-D27D59AFC1BA/Documents/Inbox/抖音广告文案-7.txt

/// 提取text文件内容
- (void)extractTextContentWithFilePaht:(NSString *)filePath {
    
    NSStringEncoding enc = CFStringConvertEncodingToNSStringEncoding(kCFStringEncodingGB_18030_2000);
    
    NSData * data = [NSData dataWithContentsOfFile:filePath];
    NSString * chapterContent = @"";
    BOOL lossy = NO;
    NSArray * enccList = @[@(NSUTF8StringEncoding), @(enc)];
    NSStringEncoding encc = [NSString stringEncodingForData:data
                                            encodingOptions:@{NSStringEncodingDetectionSuggestedEncodingsKey:enccList}
                                            convertedString:&chapterContent  usedLossyConversion:&lossy];
    DEBUGLOG(@"encc===%ld", encc);
    DEBUGLOG(@"chapterContent ===%@", chapterContent);
    
    if (!kIsEmpty(chapterContent)) {
        [self.contentTextView jk_addPlaceHolder:@""];
        self.contentTextView.text = [NSString stringWithFormat:@"%@%@", self.contentTextView.text ?: @"", chapterContent];
    } else {
        [TSWindowHudService showViewWithFailed:NSLocalizedString(@"提取失败。请稍后再试", nil)];
    }
}

Swift

func extractTextContentWithFilePaht(filePath: String) {
    let customEnc = CFStringConvertEncodingToNSStringEncoding(UInt32(CFStringEncodings.GB_18030_2000.rawValue))
    
    if let data = FileManager.default.contents(atPath: filePath) {
        let content = String.init(data: data, encoding: .utf8)
        tsPrint(content)

        var text: String = ""
        if let content = content {
            text = content
        } else {
            let contents = String.init(data: data, encoding: String.Encoding.init(rawValue: customEnc))
            tsPrint(contents)
            if let contents = contents {
                text = contents
            }
        }
        
        let vc = CreatWenAnViewController.init()
        vc.text = text
        self.navigationController?.pushViewController(vc)
    }
}