iOS实现拨打电话的方式:
方法一、requestWithURL,此方法拨打前弹出提示
NSMutableString * string = [[NSMutableString alloc] initWithFormat:@tel:%@,@136****0000];
UIWebView * callWebview = [[UIWebView alloc] init];
[callWebview loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:string]]];
[self.view addSubview:c