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iosobjective-cswiftuint8tunsafemutablepointer

Value of type 'UnsafeMutableRawPointer' has no subscripts Swift 5

I'm trying to convert objective c code into swift.

UInt8* data = calloc(bytesPerRow, height);

when I convert it in swift, It returning "UnsafeMutableRawPointer". I need of UInt8.

let data = calloc(bytesPerRow, height)! // UnsafeMutableRawPointer

I've tried different solution but didn't worked for me. Can anyone please tell me how I can resolved this issue. Thanks

Value of type 'UnsafeMutableRawPointer' has no subscripts

enter image description here

Swift Code.

 // data pointer – stores an array of the pixel components. For example (r0, b0, g0, a0, r1, g1, b1, a1 .... rn, gn, bn, an)
        //*calloc(size_t __count, size_t __size) __result_use_check __alloc_size(1,2);
        let data = calloc(bytesPerRow, height)!

        // get new RGB color space
        let colorSpace = CGColorSpaceCreateDeviceRGB()

        // create bitmap context
        let ctx = CGContext(data: data, width: width, height: height, bitsPerComponent: bitsPerComponent, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)

        // draw image into context (populating the data array while doing so)
        ctx?.draw(rawImage!, in: rect)

        // get the index of the pixel (4 components times the x position plus the y position times the row width)
        var pixelIndex = 4 * (pixelPosition.x + (pixelPosition.y * width))

        // set the pixel components to the color components
        data[pixelIndex] = color255Components[0]; // r
        data[pixelIndex+1] = color255Components[1]; // g
        data[pixelIndex+2] = color255Components[2]; // b
        data[pixelIndex+3] = color255Components[3]; // a

Objective C code.

// data pointer – stores an array of the pixel components. For example (r0, b0, g0, a0, r1, g1, b1, a1 .... rn, gn, bn, an)
    UInt8* data = calloc(bytesPerRow, height);

    // get new RGB color space
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    // create bitmap context
    CGContextRef ctx = CGBitmapContextCreate(data, width, height, bitsPerComponent, bytesPerRow, colorSpace, bitmapInfo);

    // draw image into context (populating the data array while doing so)
    CGContextDrawImage(ctx, rect, rawImage);

    // get the index of the pixel (4 components times the x position plus the y position times the row width)
    NSInteger pixelIndex = 4*(pixelPosition.x+(pixelPosition.y*width));

    // set the pixel components to the color components
    data[pixelIndex] = color255Components[0]; // r
    data[pixelIndex+1] = color255Components[1]; // g
    data[pixelIndex+2] = color255Components[2]; // b
    data[pixelIndex+3] = color255Components[3]; // a
Solution

  • You need to assign a type to your mutable pointer. In the current state it is a mutable pointer to anything but you want it to be a mutable pointer to a buffer of UInt8 values.

    To do so simply call assumingMemoryBound on your data:

    let data = calloc(bytesPerRow, height)!.assumingMemoryBound(to: UInt8.self)