UIApplication *app = [UIApplication sharedApplication];
 
NSURL *url = [NSURL URLWithString:@"Trip://com.trip.tripmobile"];
if ([app canOpenURL:url]) {
     
    NSLog(@"can  launch B app!");
    [app openURL:url];
     
}else {
     
    NSLog(@"can not launch B app!");
     
}

Trip: 为URL Schemes

com.trip.tripmobile : 为Bundle identifier 
在项目中添加URL types
URL identifier 设为 com.trip.tripmobile

URL Schemes 设置为 Trip
iOS9 要设置白名单

<key>LSApplicationQueriesSchemes</key>
 
<array>
 
        <string>Trip8080</string>
 
</array>