Ios CGAffineTransformTranslate和CGAffineTransformScale之后的UIPoints不正确

我正在使用UIKit开发简单的绘图应用程序，使用教程中共享的想法。不同之处在于，我需要实现一个功能，以便可以放大/缩放到图形中，并绘制更细的线条。我能够使用CGAffineTransformScale（当然是使用UIPinchGestureRecognitor）放大UIImage，并使用CGAffineTransform在UIImage周围移动-问题是一旦放大检测到的UITouch点，实际触摸点会有一个巨大的偏移。当我不断缩放图像时，偏移量会变大

在代码中

drawingImage-用户与之交互的图像保存图像-保存绘制的线条
transform_translate-CGAffinetransform
lastScale-CGFloat以保存上次缩放比例值
lastPoint-CGPoint以保存最后一个触摸点
lastPointForPinch-CGPoint以保存最后一个挤压点

挤压手势在viewDidLoad中初始化为-

pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchGestureDetected:)];
[self.drawingImage addGestureRecognizer:pinchGestureRecognizer];

UIPinch的检测方法是-

- (void)pinchGestureDetected:(UIPinchGestureRecognizer *)recognizer
{
    
    if([recognizer state] == UIGestureRecognizerStateBegan) {
        // Reset the last scale, necessary if there are multiple objects with different scales
        
        lastScale = [recognizer scale];
        lastPointForPinch = [recognizer locationInView:self.drawingImage];
        
    }
    
    if ([recognizer state] == UIGestureRecognizerStateBegan ||
        [recognizer state] == UIGestureRecognizerStateChanged) {
        
        CGFloat currentScale = [[[recognizer view].layer valueForKeyPath:@"transform.scale"] floatValue];
        
        // Constants to adjust the max/min values of zoom
        const CGFloat kMaxScale = 2.0;
        const CGFloat kMinScale = 1.0;
        
        CGFloat newScale = 1 -  (lastScale - [recognizer scale]);
        newScale = MIN(newScale, kMaxScale / currentScale);
        newScale = MAX(newScale, kMinScale / currentScale);
        
        CGAffineTransform transform = CGAffineTransformScale([[recognizer view] transform], newScale, newScale);

        self.savingImage.transform = transform;
        self.drawingImage.transform=transform;
        
        lastScale = [recognizer scale];  // Store the previous scale factor for the next pinch gesture call
        
        CGPoint point = [recognizer locationInView:self.drawingImage];
        transform_translate = CGAffineTransformTranslate([[recognizer view] transform], point.x - lastPointForPinch.x, point.y - lastPointForPinch.y);
        
        self.savingImage.transform = transform_translate;
        self.drawingImage.transform=transform_translate;
        lastPointForPinch = [recognizer locationInView:self.drawingImage];
        
    }
}

绘制线条的方法（仅供参考，这是一个相当标准的程序，取自上述教程，如果我在这里犯了一些错误，可以将其放在这里）-

我尝试过做CGPointApplyAffineTransform（点，变换\平移），但仍然存在巨大的偏移

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希望我的问题解释清楚，有人能帮助我。我一直在努力在这方面取得进展。提前感谢

我终于找到了解决办法……一个愚蠢的错误一再犯下。 locationInView需要来自self.view，而不是图像

@davidkonard感谢您的建议-事实上，我没有意识到（在绘图应用程序的上下文中）用户触摸屏幕的目的是在该点上绘图将完成，因此，即使UIImageView仍然移动，用户也希望在手指下绘制点/线/任何东西。所以locationInView应该是self.view（在我的例子中self.view从未被转换）

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希望这能解释我为什么会犯错误，以及我是如何想出解决办法的

您应该发布解决方案并给出代码示例。你的“我找到了解决方案”——评论说，未来的其他人无法了解你的任何信息。

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
    mouseSwiped = NO;
    UITouch *touch = [touches anyObject];
    lastPoint = [touch locationInView:self.drawingImage];
    UIGraphicsBeginImageContext(self.savingImage.frame.size);
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    mouseSwiped = YES;
    UITouch *touch = [touches anyObject];
    CGPoint currentPoint = [touch locationInView:self.drawingImage];
    CGContextRef ctxt = UIGraphicsGetCurrentContext();
    CGContextMoveToPoint(ctxt, lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(ctxt, currentPoint.x, currentPoint.y);
    CGContextSetLineCap(ctxt, kCGLineCapRound);
    CGContextSetLineWidth(ctxt, brush );
    CGContextSetRGBStrokeColor(ctxt, red, green, blue, opacity);
    CGContextSetBlendMode(ctxt,kCGBlendModeNormal);
    CGContextSetShouldAntialias(ctxt,YES);
    CGContextSetAllowsAntialiasing(ctxt, YES);
    CGContextStrokePath(ctxt);   
    self.drawingImage.image = UIGraphicsGetImageFromCurrentImageContext();
    lastPoint = currentPoint;
      
}
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
    if(!mouseSwiped) {
        UIGraphicsEndImageContext();
        UITouch *touch = [touches anyObject];
        CGPoint currentPoint = [touch locationInView:self.drawingImage];
        UIGraphicsBeginImageContext(self.drawingImage.frame.size);
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);
        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, opacity);
        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
        CGContextStrokePath(UIGraphicsGetCurrentContext());
        self.drawingImage.image = UIGraphicsGetImageFromCurrentImageContext();
        [self.drawingImage.image drawInRect:CGRectMake(0, 0, self.drawingImage.frame.size.width, self.drawingImage.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
        
    }
    UIGraphicsEndImageContext();
    UIGraphicsBeginImageContext(self.savingImage.frame.size);
    [self.savingImage.image drawInRect:CGRectMake(0, 0, self.savingImage.frame.size.width, self.savingImage.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
    [self.drawingImage.image drawInRect:CGRectMake(0, 0, self.drawingImage.frame.size.width, self.drawingImage.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
    self.savingImage.image = UIGraphicsGetImageFromCurrentImageContext();
    self.drawingImage.image=nil;
    UIGraphicsEndImageContext();
    
    }
}