iOS 打电话

1. NSString *str=[[NSMutableString alloc] initWithFormat:@"tel:%@",@"186xxxx6979"];
   [[UIApplication sharedApplication] openURL:[NSURL URLWithString:str]];

NSMutableString *str=[[NSMutableString alloc] initWithFormat:@"tel:%@",@"186xxxx6979"];
UIWebView *callWebview = [[UIWebView alloc] init];
[callWebview loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:str]]];
[self.view addSubview:callWebview];

NSMutableString* str=[[NSMutableString alloc] initWithFormat:@"telprompt://%@",@"186xxxx6979"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:str]];

经过测试，在iOS 10.2上，这几种方式没有区别，展示出来都有弹框，都是回到原app.