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Google API由經緯度查高度的iPhone程式

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三, 03/30/2011 - 18:45 — 匿名者

Google API由經緯度查高度的iPhone程式：2011年03月21日星期一

iPhone程式中若有了經緯度值，想找高度(離海平面標高)，可用Google API，詳見Google Elevation API 一文。 下段程式碼即是：

  1. NSStringEncoding enc;
  2. NSError*error = [[[NSErroralloc] init] autorelease];
  3. NSString*altitudeGetter = [NSString stringWithContentsOfURL :[NSURLURLWithString: @"http://maps.google.com/maps/api/elevation/xml?locations=39.7391536,-104.9847034&sensor=true"] usedEncoding:&enc error:&error ];
  4. NSLog(@"the xml = %@ -- \n", altitudeGetter);

1,2行是先定兩個var給第三行用。

第三行即為使用經緯度值呼叫Google API，用stringWithContentsOfURL從http://maps.google.com/maps/api/elevation 取得高度(離海平面標高)，/xml表示output為xml format，?locations=39.7391536,-104.9847034則是經、緯(latitude、longitude)度值，&sensor=true表示iPhone有GPS， usedEncoding:&enc將Encode方式回傳至enc，error:&error將error狀態回傳至error。

第四行將自Google Elevation API的xml列印出來如下：

由上xml，可以看到<eleveation>1608.6379395</elevation>顯示經、緯(latitude、longitude)度{39.7391536, -104.9847034}的高度(離海平面標高)為1608.6379395。

注意事項：

  1. 不需使用Google API金鑰。