Firebase MLKit文本识别错误 [英] Firebase MLKit Text Recognition Error

问题描述

我正在尝试使用Firebase MLKit OCR我的图像，但是它失败并返回错误

I'm trying to OCR my image using Firebase MLKit but it fails and return with error

文本检测失败，并显示错误:由于self为nil，因此无法运行文本检测器.

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)
    }
}

推荐答案

您似乎需要保持对textDetector的强引用，否则检测器会在可以调用完成块之前被释放.

It looks like you need to keep a strong reference to textDetector, otherwise the detector gets released before the completion block can be called.

稍微更改代码:

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
    }
}

您还可以将其解包，以确保分配后它不为零:

You can also unwrap it to make sure it's not nil after you assign it:

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

希望对您有帮助！

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