如何使用自动布局在 MKAnnotation 中显示多行?

问题描述

我正在使用 mapkit 如何在 MKAnnotation 视图中使用多行.

i am using mapkit how i can multiple line in MKAnnotation view.

那里的每个注释都有标题和副标题.我如何在 auto layout 的帮助下显示多行副标题?

Every annotation there has title and subtitle. how i show sub title with multiple line with the help of auto layout ?

我找到了答案.请尝试我的答案.我们只需要在

i found it's Answer .plz try my answer. we just need to do code in

- (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id <MKAnnotation>)annotation
{   

}

这里我展示了如何将自动布局与 MKAnnotation 一起使用.

here i show the idea how to use autolayout with MKAnnotation .

推荐答案

借助自动布局，我们可以在MKAnnotation视图中显示多行

we can show multiple line in MKAnnotation view With the help of auto layout

这很简单.

在目标c

 - (MKAnnotationView *) mapView:(MKMapView *)mapView viewForAnnotation:(id<MKAnnotation>)annotation {

        if ([annotation isKindOfClass:[MKUserLocation class]])
            return nil;
        if ([annotation isKindOfClass:[CustomAnnotation class]]) {
            CustomAnnotation *customAnnotation = (CustomAnnotation *) annotation;

            MKAnnotationView *annotationView = [mapView dequeueReusableAnnotationViewWithIdentifier:@"CustomAnnotation"];

            if (annotationView == nil)
                annotationView = customAnnotation.annotationView;
            else
                annotationView.annotation = annotation;

            //Adding multiline subtitle code 

            UILabel *subTitlelbl = [[UILabel alloc]init];
            subTitlelbl.text = @"sri ganganagar this is my home twon.sri ganganagar this is my home twon.sri ganganagar this is my home twon.  ";

            annotationView.detailCalloutAccessoryView = subTitlelbl;

            NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:subTitlelbl attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationLessThanOrEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:150];

             NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:subTitlelbl attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:nil attribute:NSLayoutAttributeNotAnAttribute multiplier:1 constant:0];
            [subTitlelbl setNumberOfLines:0];
            [subTitlelbl addConstraint:width];
            [subTitlelbl addConstraint:height];




            return annotationView;
        } else
            return nil;
    }

输出

对于斯威夫特

func mapView(mapView: MKMapView, viewForAnnotation annotation: MKAnnotation) -> MKAnnotationView? {

        let identifier = "MyPin"

        if annotation.isKindOfClass(MKUserLocation) {
            return nil
        }

        var annotationView: MKPinAnnotationView? = mapView.dequeueReusableAnnotationViewWithIdentifier(identifier) as? MKPinAnnotationView

        if annotationView == nil {

            annotationView = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
            annotationView?.canShowCallout = true

              let label1 = UILabel(frame: CGRectMake(0, 0, 200, 21))
            label1.text = "Some text1 some text2 some text2 some text2 some text2 some text2 some text2"
             label1.numberOfLines = 0
              annotationView!.detailCalloutAccessoryView = label1;

            let width = NSLayoutConstraint(item: label1, attribute: NSLayoutAttribute.Width, relatedBy: NSLayoutRelation.LessThanOrEqual, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 200)
            label1.addConstraint(width)


            let height = NSLayoutConstraint(item: label1, attribute: NSLayoutAttribute.Height, relatedBy: NSLayoutRelation.Equal, toItem: nil, attribute: NSLayoutAttribute.NotAnAttribute, multiplier: 1, constant: 90)
            label1.addConstraint(height)



        } else {
            annotationView!.annotation = annotation
        }
        return annotationView
    }


}

这里我使用 NSLayoutConstraint

我以编程方式创建标签.在其上添加约束，然后在MKAnnotationView的detailCalloutAccessoryView中添加标签.

i programatically create a label. add the constraint on it and then add the label in detailCalloutAccessoryView of MKAnnotationView.

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