iOS触摸绘图开发遇报错：Cannot call value of non-function type `[Float]`求助

Hey there! Let's break down what's going wrong and how to fix it, plus a cleaner way to store your touch points for your drawing app.

Why You're Getting That Error #

The error Cannot call value of non-function type [Float] pops up because you're trying to access array elements with parentheses pointsX(0) instead of square brackets pointsX[0]. But even fixing that syntax, storing X and Y coordinates in separate arrays is clunky—you have to manually keep both arrays in sync, which is easy to mess up.

Better Solution: Use a Single [CGPoint] Array #

Instead of two separate arrays for X and Y values, store your touch points directly as CGPoint instances in one array. This keeps your coordinates paired correctly, simplifies working with UIBezierPath, and makes your code more intuitive.

Modified Code Example #

First, replace your existing pointsX and pointsY arrays with a single array for CGPoint:

var touchPoints: [CGPoint] = []
var touchIndicators: [UIView] = []
var draw = true // Assuming this is your drawing mode toggle

Update your touchesBegan method to store full CGPoint values instead of splitting coordinates:

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard draw else { return }
    
    for touch in touches {
        let location = touch.location(in: view)
        touchPoints.append(location) // Store the complete touch point
        
        // Add your touch indicator view (unchanged from your original code)
        let touchIndicator = UIView(frame: CGRect(x: location.x - 10, y: location.y - 10, width: 20, height: 20))
        touchIndicator.alpha = 0.8
        touchIndicator.backgroundColor = .red
        touchIndicator.layer.cornerRadius = 10
        view.addSubview(touchIndicator)
        touchIndicators.append(touchIndicator)
        
        // Trigger drawing once we have 2 or more points
        if touchPoints.count >= 2 {
            drawFilledShape()
        }
    }
}

Add a helper method to dynamically create and render the filled shape using your touchPoints array:

func drawFilledShape() {
    guard touchPoints.count >= 2 else { return }
    
    // Build the bezier path from your collected touch points
    let shapePath = UIBezierPath()
    shapePath.move(to: touchPoints[0]) // Start at the first touch point
    
    // Add lines to every subsequent point
    for point in touchPoints.dropFirst() {
        shapePath.addLine(to: point)
    }
    
    shapePath.close() // Close the path to form a closed, fillable shape
    
    // Create a shape layer to render the path
    let shapeLayer = CAShapeLayer()
    shapeLayer.path = shapePath.cgPath
    shapeLayer.fillColor = UIColor.red.cgColor
    shapeLayer.strokeColor = UIColor.black.cgColor // Optional: add a border
    shapeLayer.lineWidth = 2 // Optional: adjust border thickness
    
    // Add the layer to your view's layer hierarchy
    view.layer.addSublayer(shapeLayer)
}

Key Improvements #

• No more coordinate sync errors: each touch point is stored as a single, unified CGPoint
• Dynamic shape building: the helper method automatically uses all collected points to form the shape
• Cleaner code structure: separating drawing logic into a helper method makes it easier to update or extend later
• Safety checks: guard statements ensure we only attempt to draw when we have enough points

内容的提问来源于stack exchange，提问作者Josef