drawRect 和 setNeedsDisplay 永远不会被调用

Question

为其分配手势

我添加了一个 uiview （带有 uimageview 的holderview）作为子视图，并使用imageview = [[UIImageView alloc] initWithFrame:[holderView frame]]; [imageview setImage:cppobject->OutputImage]; imageview.contentMode = UIViewContentModeScaleAspectFit;

[holderView addSubview:imageview];
holderView.contentMode = UIViewContentModeScaleAspectFit ;

UIPinchGestureRecognizer *pinchRecognizer = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scale:)];
[pinchRecognizer setDelegate:self];
[holderView addGestureRecognizer:pinchRecognizer];
[pinchRecognizer release];

UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotate:)];
[rotationRecognizer setDelegate:self];
[holderView addGestureRecognizer:rotationRecognizer];
[rotationRecognizer release];

panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(move:)];
[panRecognizer setMinimumNumberOfTouches:1];
[panRecognizer setMaximumNumberOfTouches:1];
[panRecognizer setDelegate:self];
[holderView addGestureRecognizer:panRecognizer];
holderView.tag=101;
[self.view addSubview:holderView];
[holderView sizeToFit];
[self AddInformation];
[holderView retain];
[self retain];

然后在 panRecognizer 函数（移动）中我想使用画线

         UIPanGestureRecognizer *gR = (UIPanGestureRecognizer *) sender ; 


        NSValue *value = [NSValue valueWithCGPoint: [gR locationInView:gR.view]]; 





        [Points addObject:value];


        [holderView setNeedsDisplay];

        NSLog(@"End of measuring") ; 

，我将使用 Points 中的点在

-(void)drawRect:(CGRect)rect 中的所有子视图上方画线 { NSLog(@"在矩形中输入绘图");

if (Measuring) {

    [[UIColor redColor] setStroke];

    UIBezierPath *pathToDraw = [UIBezierPath bezierPath]; 

    for (int n = 1; n < [Points count] - 1 ; n++) { 

    NSValue * value = [Points objectAtIndex:(NSInteger)n];

        CGPoint  point = [value CGPointValue]; 

        [pathToDraw moveToPoint:point];


        value = [Points objectAtIndex:(NSInteger)n+1];

        point = [value CGPointValue];

        [pathToDraw addLineToPoint:point];



    }



    [pathToDraw stroke];







}

问题

是 [holderView setNeedsDisplay];永远不要致电或解雇任何有关该问题的建议或帮助

Answer 1

您需要子类化UIView并在子类中实现drawRect。

然后，在创建holderview时，请确保实例化您的子类UIView，而不是默认的UIView。