ios - Firebase MLKit 文本识别错误

Question

我正在尝试使用 Firebase MLKit 对我的图像进行 OCR，但失败并返回错误

Text detection failed with error: Failed to run text detector because self is nil.

/// Detects texts on the specified image and draws a frame for them.
func detectTexts() {
    let image = #imageLiteral(resourceName: "testocr")
    // Create a text detector.
    let textDetector = vision.textDetector()  // Check console for errors.

    // Initialize a VisionImage with a UIImage.
    let visionImage = VisionImage(image: image)
    textDetector.detect(in: visionImage) { (features, error) in
        guard error == nil, let features = features, !features.isEmpty else {
            let errorString = error?.localizedDescription ?? "No results returned."
            print("Text detection failed with error: \(errorString)")
            return
        }

        // Recognized and extracted text
        print("Detected text has: \(features.count) blocks")
        let resultText = features.map { feature in
            return "Text: \(feature.text)"
            }.joined(separator: "\n")
        print(resultText)
    }
}

Answer 1

看起来您需要保持对 textDetector 的强引用，否则检测器会在调用完成 block 之前被释放。

稍微更改一下代码:

var textDetector: VisionTextDetector?   // NEW

/// Detects texts on the specified image and draws a frame for them.
func detectTexts() {
    // ... truncated ...
    textDetector = vision.textDetector()   // NEW
    let visionImage = VisionImage(image: image)
    textDetector?.detect(in: visionImage) { (features, error) in   // NEW
        // Callback implementation
    }
}

你也可以解开它以确保它在你赋值后不为 nil:

guard let textDetector = textDetector else { 
    print("Error: textDetector is nil.")
    return
}

希望对您有所帮助!