ios调用phone call

The iphone will dial a number using either of the formats listed below. But, it will do nothing if you are in the simulator

[[UIApplication sharedApplication]
                    openURL:[NSURL URLWithString:@"tel://15415551234"]];

[[UIApplication sharedApplication]
                    openURL:[NSURL URLWithString:@"tel:15415551234"]];

[[UIApplication sharedApplication]
                    openURL:[NSURL URLWithString:@"tel:1-541-555-1234"]];