在程序中调用系统自带的应用，比如我进入程序的时候，希望直接调用safar来打开一个网页，下面是一个简单的使用：

查看更多iPhone应用程序的调用和第三方应用程序的调用，可以在iPhone的URL方案查看。下面列举部分：

Apple iPhone Applications
Safari
Any URL starting with http:// which does not point to maps.google.com or www.youtube.com is sent to Safari:

NSString *stringURL = @"http://wiki.akosma.com/";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
Apparently feed:// opens http://reader.mac.com in Safari.

Maps

//调用系统自带地图
    NSString *title = @"title";
    float latitude = 35.4634;
    float longitude = 9.43425;
    int zoom = 13;
    NSString *stringURL = [NSString stringWithFormat:@"http://maps.apple.com/?q=%@@%1.6f,%1.6f&z=%d", title, latitude, longitude, zoom];
    NSURL *url = [NSURL URLWithString:stringURL];
    [[UIApplication sharedApplication] openURL:url];

//调用高德地图，如果没有下载应用就调用不了
    NSString *title = @"title";
    float latitude = 35.4634;
    float longitude = 9.43425;
    int zoom = 13;
    NSString *stringURL = [NSString stringWithFormat:@"http://ditu.amap.com//maps?q=%@@%1.6f,%1.6f&z=%d", title, latitude, longitude, zoom];
    NSURL *url = [NSURL URLWithString:stringURL];
    [[UIApplication sharedApplication] openURL:url];

Phone
The phone links start with "tel:" but must not contain spaces or brackets (it can contain dashes and "+" signs, though):

NSMutableString *phone = [@"+ 12 34 567 89 01" mutableCopy];
[phone replaceOccurrencesOfString:@" "
                       withString:@""
                          options:NSLiteralSearch
                            range:NSMakeRange(0, [phone length])];
[phone replaceOccurrencesOfString:@"("
                       withString:@""
                          options:NSLiteralSearch
                            range:NSMakeRange(0, [phone length])];
[phone replaceOccurrencesOfString:@")"
                       withString:@""
                          options:NSLiteralSearch
                            range:NSMakeRange(0, [phone length])];
NSURL *url = [NSURL URLWithString:[NSString stringWithFormat:@"tel:%@", phone]];
[[UIApplication sharedApplication] openURL:url];

SMS调用系统的短信
To open the SMS application, just use the sms: protocol in your URL:

NSString *stringURL = @"sms:";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
You can specify a phone number, but apparently not a default text for your message:

NSString *stringURL = @"sms:+12345678901";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

The same restrictions apply as for phone URLs, regarding spaces, brackets and dashes.

Mail
These URLs launch Mail and open the compose message controller:

NSString *stringURL = @"mailto:test@example.com";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
You can also provide more information, for a customized subject and body texts:

NSString *subject = @"Message subject";
NSString *body = @"Message body";
NSString *address = @"test1@akosma.com";
NSString *cc = @"test2@akosma.com";
NSString *path = [NSString stringWithFormat:@"mailto:%@?cc=%@&subject=%@&body=%@", address, cc, subject, body];
NSURL *url = [NSURL URLWithString:[path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:url];
You might also omit some information:

NSString *subject = @"Message subject";
NSString *path = [NSString stringWithFormat:@"mailto:?subject=%@", subject];
NSURL *url = [NSURL URLWithString:[path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
[[UIApplication sharedApplication] openURL:url];
For more complex body texts, you might want to use the CFURLCreateStringByAddingPercentEscapes() function, as explained above in this page.

YouTube
URLs starting with http://www.youtube.com open up the "YouTube" application automatically:

NSString *stringURL = @"http://www.youtube.com/watch?v=WZH30T99MaM";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
It also works with this URL (which normally brings the Flash video player used by YouTube):

NSString *stringURL = @"http://www.youtube.com/v/WZH30T99MaM";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

iTunes音乐

NSString *stringURL = @"http://phobos.apple.com/WebObjects/MZStore.woa/wa/viewAlbum?i=156093464&id=156093462&s=143441";
    NSURL *url = [NSURL URLWithString:stringURL];
    [[UIApplication sharedApplication] openURL:url];

App Store
Very similar to the iTunes URLs:

NSString *stringURL = @"http://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=294409923&mt=8";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

iBooks
(source: http://akos.ma/aqdr)

NSString *stringURL = @"itms-books:";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

NSString *stringURL = @"itms-bookss:";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

Third Party Applications
Most URL schemes in this list come from App Lookup.

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AirSharing一款可以把iPhone变成一个网络驱动器，使得文件能够在手机与你的电脑之间进行无线来回传送，同时可以让你在自己的手机上打开浏览多种类型的文件。
Launch the application:

NSString *stringURL = @"airsharing://";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

Alocola 金山词霸
Launch the application:

NSString *stringURL = @"alocola://";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

Appigo Notebook
Launch the application:

NSString *stringURL = @"appigonotebook://";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

Appigo Todo
Launch the application:

NSString *stringURL = @"appigotodo://";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
Create a new task:

NSString *template = @"appigotodo://com.example.xyzapp/import?name=%@&note=%@&due-date=%@&priority=%@&repeat=%@";
NSString *name = @"Buy%20some%20milk";
NSString *note = @"Stop%20on%20the%20way%20home%20from%20work.";
NSString *dueDate = @"2009-07-16";
NSString *priority = @"1";
NSString *repeat = @"101";
NSString *stringURL = [NSString stringWithFormat:template, name, note, dueDate, priority, repeat];
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];

Duo
Launch the application and pre-populate the update field with your desired Tweet/Facebook update. Optional: Provide Duo with the custom URL and return path to your app to provide the user with a button to return to your app.

NSString *appID = @"Your Apps Name";
NSString *updateInfo = @"The Tweet/Status Update";
NSString *returnScheme = @"Your Apps Return URL Scheme";
NSString *returnPath = @"Your/Apps/Return/Path";
NSString *baseURL = @"duoxx://updateFaceTwit?";
 NSString *encodedUpdateInfo = [updateInfo stringByAddingPercentEscapesUsingEncoding:NSASCIIStringEncoding];
NSString *urlString = [NSString stringWithFormat:@"%@BLappID=%@;BLupdateInfo=%@;BLreturnScheme=%@;BLreturnPath=%@",
         baseURL, appID, encodedUpdateInfo, returnScheme, returnPath];

NSURL *url = [NSURL URLWithString:urlString];
[[UIApplication sharedApplication] openURL:url];

The Cartographer
Launch app and add a placemark at given coordinate:

NSString *title = @"Placemark title (optional)";
NSString *summary = @"Placemark description (optional)";
CLLocationCoordinate2D coordinate = CLLocationCoordinate2DMake(123.0, 12.0);

title = [(id)CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)title, NULL, (CFStringRef)@";/?:@&=+$,", kCFStringEncodingUTF8) autorelease];
summary = [(id)CFURLCreateStringByAddingPercentEscapes(NULL, (CFStringRef)summary, NULL, (CFStringRef)@";/?:@&=+$,", kCFStringEncodingUTF8) autorelease];

NSString *cartographerURL = [NSString stringWithFormat:@"cartographer://placemark?coordinate=%lf,%lf&title=%@&summary=%@",
         coordinate.latitude, coordinate.longitude, title, summary];

NSURL *url = [NSURL URLWithString:cartographerURL];
[[UIApplication sharedApplication] openURL:url];

Launch app and load either a KML source or a Google My Map:

NSString *sourceURL = @"http://....";
// e.g. http://maps.google.com/maps/ms?ie=UTF8&hl=en&msa=0&msid=208320711678395936256.00046bbcfdcd1f3ebf64b&z=5

// Optional:
MKCoordinateRegion region = ...;
sourceURL = [sourceURL stringByAppendingFormat:@"&ll=%lf,%lf&spn=%lf,%lf",
               region.center.latitude, region.center.longitude, region.span.latitudeDelta, region.span.longitudeDelta];

NSURL *url = [NSURL URLWithString:[sourceURL stringByReplacingOccurrencesOfString:@"http://" withString:@"cartographer://"]];
[[UIApplication sharedApplication] openURL:url];

ChatCo

NSString *stringURL = @"irc://irc.example.domain/roomName";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
NSString *stringURL = @"irc://irc.example.domain/Nickname@roomName";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];
NSString *stringURL = @"irc://irc.example.domain/Nickname!Realname@roomName";
NSURL *url = [NSURL URLWithString:stringURL];
[[UIApplication sharedApplication] openURL:url];