[[UIApplication sharedApplication] openURL:url];
通過給url不同的值，可以實現呼叫系統自帶 電話／簡訊／郵箱／瀏覽器／...

1、呼叫 電話phone
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel://800888"]];
撥打電話之後不跳轉回app
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"telprompt://800888"]];
撥打電話之後跳轉回app

2、呼叫自帶 瀏覽器safari
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://www.abt.com"]];

3、呼叫 自帶Mail
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"mailto://

[email protected]"]];

4、呼叫 簡訊
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"sms://800888"]];

5、呼叫 app Store
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-apps://"]];

6、呼叫 iBook
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"itms-books://"]];

7、呼叫 Map
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"maps://"]];

8、呼叫 Facetime
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"facetime://"]];

9、呼叫 Music
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"music://"]];

10、跳轉到系統設定相關介面
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"prefs:root=WIFI"]];

以下為設定的跳轉關鍵字
About — prefs:root=General&path=About
Accessibility — prefs:root=General&path=ACCESSIBILITY
Airplane Mode On — prefs:root=AIRPLANE_MODE
Auto-Lock — prefs:root=General&path=AUTOLOCK
Brightness — prefs:root=Brightness
Bluetooth — prefs:root=General&path=Bluetooth
Date & Time — prefs:root=General&path=DATE_AND_TIME
FaceTime — prefs:root=FACETIME
General — prefs:root=General
Keyboard — prefs:root=General&path=Keyboard
iCloud — prefs:root=CASTLE
iCloud Storage & Backup — prefs:root=CASTLE&path=STORAGE_AND_BACKUP
International — prefs:root=General&path=INTERNATIONAL
Location Services — prefs:root=LOCATION_SERVICES
Music — prefs:root=MUSIC
Music Equalizer — prefs:root=MUSIC&path=EQ
Music Volume Limit — prefs:root=MUSIC&path=VolumeLimit
Network — prefs:root=General&path=Network
Nike + iPod — prefs:root=NIKE_PLUS_IPOD
Notes — prefs:root=NOTES
Notification — prefs:root=NOTIFICATIONS_ID
Phone — prefs:root=Phone
Photos — prefs:root=Photos
Profile — prefs:root=General&path=ManagedConfigurationList
Reset — prefs:root=General&path=Reset
Safari — prefs:root=Safari
Siri — prefs:root=General&path=Assistant
Sounds — prefs:root=Sounds
Software Update — prefs:root=General&path=SOFTWARE_UPDATE_LINK
Store — prefs:root=STORE
Twitter — prefs:root=TWITTER
Usage — prefs:root=General&path=USAGE
VPN — prefs:root=General&path=Network/VPN
Wallpaper — prefs:root=Wallpaper
Wi-Fi — prefs:root=WIFI
INTERNET_TETHERING Internet_tethering — prefs:root= INTERNET_TETHERING