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iosobjective-cimageimage-rotation

Rotate Image on Slider Value in iOS

I am rotating the image on slider value -

I am using this code for rotation - 

editingView.transform = CGAffineTransformRotate(editingView.transform,sliderVal);

its Rotating properly but if i am trying to move or resize after rotation,The editingView is resizing with unexpected behavior and view disappears from screen.

Please suggest me what i am doing wrong.

Solution

  • Well whenever you rotate a view which is inside a superview, you should preserve the position of the view. If you are not rotating any view across the origin then, you should first translate the view's origin to the superview's origin and then rotate and then again translate back to the original point.

    • Find the coordinate if the view you want to rotate with respect to its superview, say it (x,y).

    • Translate the view to the origin as;

      view.transform = CGAffineTransformMakeTranslation(x,y)

    • Rotate the view by some angle, say PI,

      view.transform = CGAffineTransformMakeRotation(PI)

    • After rotation translate back to the original point as;

      view.transform = CGAffineTransformMakeTranslation(-x,-y)

    And that's it. It should work with all the different rotation.