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我正在尝试为拖动的 MKAnnotationPin 的位置添加某种指示器。

到目前为止，我想出了以下无效的解决方案：

- (void) showDragLoc{


UIView *cross = [[UIView alloc] initWithFrame:CGRectMake(dragPin.center.x, dragPin.center.y, 10, 10)];
[self.mapView addSubview:cross];
while(dragPin.dragState  == MKAnnotationViewDragStateDragging){

    [UIView beginAnimations:nil context:NULL]; // animate the following:
    cross.frame = CGRectMake(dragPin.center.x, dragPin.center.y, 10, 10); // move to new location
    [UIView setAnimationDuration:0.3];
    [UIView commitAnimations];
}
}

ere dragPin 是在标题中声明的 MKAnnotationView。当 pin 的 dragState 转到 MKAnnotationViewDragStateDragging（来自委托方法）时，调用此函数。

我的目标是添加某种指示当前被拖动的针脚所在位置的指示器。

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1 回答 1

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如果你想在标准中添加一个十字准线MKPinAnnotationView，你应该继承它，然后在你的实现中添加你的十字准线setDragState:animated:。

因此，要子类化，请创建一个新类，例如PinWithCrosshairAnnotationView. .h 公共接口不需要太多：

@interface PinWithCrosshairAnnotationView : MKPinAnnotationView

@end

.m 实现只是实现了一个setDragState:animated:添加你的十字准线的实现，然后调用super实现来获取引脚拉拔和放下功能。如果旗子打开，我也在制作动画animated，但你不必这样做。您的frame坐标无疑会与我的不同，但我从您上面的代码示例中收集到您已经为十字准线图像找到了正确的值：

#import "PinWithCrosshairAnnotationView.h"

@interface PinWithCrosshairAnnotationView ()
@property (nonatomic, weak) UIImageView *crosshairImageView;
@end

@implementation PinWithCrosshairAnnotationView

- (void)setDragState:(MKAnnotationViewDragState)newDragState animated:(BOOL)animated
{
    if (newDragState == MKAnnotationViewDragStateStarting)
    {
        // create the crosshair imageview and add it as a subview

        UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(-1.5, 30, 17.5, 17.5)];
        imageView.image = [UIImage imageNamed:@"Crosshairs.png"];
        [self addSubview:imageView];

        // if the animated flag is on, we'll fade it to visible state

        if (animated)
        {
            imageView.alpha = 0.0;
            [UIView animateWithDuration:0.2
                             animations:^{
                                 imageView.alpha = 1.0;
                             }];
        }

        // save a reference to that imageview in a class property

        self.crosshairImageView = imageView;
    }
    else if (newDragState == MKAnnotationViewDragStateEnding || newDragState == MKAnnotationViewDragStateCanceling)
    {
        if (animated)
        {
            // if we're animating, let's quickly fade it to invisible
            // and in the completion block, we'll remove it

            [UIView animateWithDuration:0.2
                             animations:^{
                                 self.crosshairImageView.alpha = 0.0;
                             }
                             completion:^(BOOL finished) {
                                 [self.crosshairImageView removeFromSuperview];
                                 self.crosshairImageView = nil;
                             }];
        }
        else
        {
            // if we're not animating, just remove it

            [self.crosshairImageView removeFromSuperview];
            self.crosshairImageView = nil;
        }
    }

    // remember to call super so we get all the other wonderful superclass behavior

    [super setDragState:newDragState animated:animated];
}
@end

显然，您将相应地viewForAnnotation在您的MKMapView委托中自定义。这是一个极简版本，但您显然会根据您的需要（标注、标题、副标题等）进行调整：

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation
{
    if ([annotation isKindOfClass:[MKUserLocation class]])
        return nil;

    MKAnnotationView *view = [[PinWithCrosshairAnnotationView alloc] initWithAnnotation:annotation
                                                                        reuseIdentifier:@"pinwithcrosshairannotation"];
    view.draggable = YES;
    view.canShowCallout = NO;

    return view;
}
于 2013-02-27T03:58:23.887 回答