以编程方式放大MKMapView [英] Zoom in a MKMapView programmatically

问题描述

我正在iPhone应用程序中使用MKMapView.当我单击一个按钮时，缩放级别必须增加.这是我的第一种方法:

I'm using a MKMapView inside an iPhone app. When I click a button the zoom level must increase. This is my first approach:

MKCoordinateRegion zoomIn = mapView.region;
zoomIn.span.latitudeDelta *= 0.5;
[mapView setRegion:zoomIn animated:YES];

但是，此代码无效，因为我没有更新longitudeDelta值.所以我添加了这一行:

However, this code had no effect, since I didn't update the longitudeDelta value. So I added this line:

zoomIn.span.longitudeDelta *= 0.5;

现在它可以工作，但仅在某些情况下可以. latitudeDelta和longitudeDelta不会以相同的方式更改，我的意思是，它们的值不成比例.知道如何解决这个问题吗?

Now it works, but only sometimes. The latitudeDelta and longitudeDelta don't change in the same way, I mean, their values are not proportional. Any idea how to solve this?

推荐答案

我不知道这是否是正确的方法，但是我正在使用它来放大和缩小.

I have no idea if this is the right way to do it, but I'm using this to zoom in and out.

        case 0: { // Zoom In
        //NSLog(@"Zoom - IN");
        MKCoordinateRegion region;
        //Set Zoom level using Span
        MKCoordinateSpan span;  
        region.center=mapView.region.center;

        span.latitudeDelta=mapView.region.span.latitudeDelta /2.0002;
        span.longitudeDelta=mapView.region.span.longitudeDelta /2.0002;
        region.span=span;
        [mapView setRegion:region animated:TRUE];
    }
        break;

    // Zoom Out 
    case 2: {
        //NSLog(@"Zoom - OUT");
        MKCoordinateRegion region;
        //Set Zoom level using Span
        MKCoordinateSpan span;  
        region.center=mapView.region.center;
        span.latitudeDelta=mapView.region.span.latitudeDelta *2;
        span.longitudeDelta=mapView.region.span.longitudeDelta *2;
        region.span=span;
        [mapView setRegion:region animated:TRUE];
    }

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