我使用 Titanium Appcelerator 制作了一个基于地图的应用程序。我在地图上显示用户的当前位置。我还有一个文本框，我在其中获取用户所需的位置，以便在地图上显示它。为了在地图上显示特定位置，我使用了注释并且工作正常。问题是，当文本框的值发生变化时，会在地图上创建另一个注释。我想要做的是，我想在放置新注释之前清除以前的注释。我的 app.js 文件如下所示：
应用程序.js：
//create the window
var win1 = Titanium.UI.createWindow({
title:'Exercise Tracker',
backgroundColor: '#000'
});
//goto location label
var location_label = Titanium.UI.createLabel({
left:'10',
top:'20',
text:'Go to: ',
font:{fontSize:20}
})
//goto location textbox
var location_textbox= Titanium.UI.createTextField({
top: '15',
left: '85',
width: '300',
height: '50',
})
//go button
var btnGo=Ti.UI.createButton(
{
top:'15',
left:'420',
width:'50',
height:'50',
title:"Go"
})
//create our mapview
var mapview = Titanium.Map.createView({
top: 110,
height: 'auto',
width: 'auto',
mapType: Titanium.Map.STANDARD_TYPE,
region: {latitude: 51.50015,
longitude:-0.12623,
latitudeDelta:0.5,
longitudeDelta:0.5},
animate: true,
regionFit: true,
userLocation: true,
});
// to get values from both the textbox
btnGo.addEventListener('click', function (e){
//var addr=location_textbox.value;
var addr="";
addr = location_textbox.value;
annote(addr);
});
// to refrsh the page on click textbox
location_textbox.addEventListener('click', function (e){
});
//--------------------------annotations--------------------------------
//var addr = 'Howrah';
function annote(addr)
{
var addr_fw=addr;
Titanium.Geolocation.forwardGeocoder(addr,function(evt) {
var objLocationAnnotation = Titanium.Map.createAnnotation({
latitude: evt.latitude,
longitude: evt.longitude,
title: addr_fw
});
mapview.addAnnotation(objLocationAnnotation);
});
}
//--------------------------annotations--------------------------------
//add the map to the window
win1.add(mapview);
//set the distance filter
Titanium.Geolocation.distanceFilter = 10;
Titanium.Geolocation.getCurrentPosition(function(e)
{
if (e.error)
{
//if mapping location doesn't work, show an alert
alert('Sorry, but it seems geo location is not available on your device!');
return;
}
//get the properties from Titanium.GeoLocation
var longitude = e.coords.longitude;
var latitude = e.coords.latitude;
var altitude = e.coords.altitude;
var heading = e.coords.heading;
var accuracy = e.coords.accuracy;
var speed = e.coords.speed;
var timestamp = e.coords.timestamp;
var altitudeAccuracy = e.coords.altitudeAccuracy;
//apply the lat and lon properties to our mapview
mapview.region = {latitude: latitude,
longitude: longitude,
latitudeDelta:0.5,
longitudeDelta:0.5
};
});
//finally, open the window
win1.open();
//adding display properties to the main window
win1.add(location_label);
win1.add(location_textbox);
win1.add(btnGo);