單點讓UIView同時縮放與旋轉

UITouch *touch1 = [sortedTouches objectAtIndex:0]; //觸控移動的點

        CGPoint beginPoint1 = *(CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch1);

        CGPoint currentPoint1 = [touch1 locationInView:self.superview];

        double layerX = self.center.x;//指定UIView的中心點

        double layerY = self.center.y;//指定UIView的中心點

        double x1 = beginPoint1.x - layerX;

        double y1 = beginPoint1.y - layerY;

        double x2 = layerX - layerX;

        double y2 = layerY - layerY;

        double x3 = currentPoint1.x - layerX;

        double y3 = currentPoint1.y - layerY;

        double x4 = layerX - layerX;

        double y4 = layerY - layerY;

        

        double D = (y1-y2)*(y1-y2) + (x1-x2)*(x1-x2);

        if (D < 0.1) {

            return CGAffineTransformMakeTranslation(x3-x1, y3-y1);

        }

        

        double a = (y1-y2)*(y3-y4) + (x1-x2)*(x3-x4);

        double b = (y1-y2)*(x3-x4) - (x1-x2)*(y3-y4);

        double tx = (y1*x2 - x1*y2)*(y4-y3) - (x1*x2 + y1*y2)*(x3+x4) + x3*(y2*y2 + x2*x2) + x4*(y1*y1 + x1*x1);

        double ty = (x1*x2 + y1*y2)*(-y4-y3) + (y1*x2 - x1*y2)*(x3-x4) + y3*(y2*y2 + x2*x2) + y4*(y1*y1 + x1*x1);

        

self.transform = CGAffineTransformMake(a/D, -b/D, b/D, a/D, tx/D, ty/D);//把變動過後的矩陣給View的