如何使用autolayout在MKAnnotation中显示多行？

Question

我正在使用mapkit如何在MKAnnotation视图中多行.

每个注释都有标题和副标题.我如何在自动布局的帮助下显示多行的子标题？

我发现它是答案.plz尝试我的答案.我们只需要编写代码

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

}

在这里,我展示了如何使用自动布局与MKAnnotation.

Answer 1

添加多行的扩展名:

import MapKit // must import MapKit for MKAnnotationView to get recognized

extension MKAnnotationView {

    func loadCustomLines(customLines: [String]) {
        let stackView = self.stackView()
        for line in customLines {
            let label = UILabel()
            label.text = line
            stackView.addArrangedSubview(label)
        }
        self.detailCalloutAccessoryView = stackView
    }



    private func stackView() -> UIStackView {
        let stackView = UIStackView()
        stackView.axis = .vertical
        stackView.distribution = .fillEqually
        stackView.alignment = .fill
        return stackView
    }
}

使用:

view = MKPinAnnotationView(annotation: annotation, reuseIdentifier: identifier)
view.canShowCallout = true
view.loadCustomLines(customLines: ["qqqq", "wwww", "eee"])

Answer 2

我们可以在MKAnnotation视图中显示多行,借助自动布局

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;
    }

产量

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
    }


}

在这里我使用 NSLayoutConstraint

我以编程方式创建了一个标签.在其上添加约束,然后在MKAnnotationView的detailCalloutAccessoryView中添加标签.