iOS 10以前
NSString *phoneStr = [NSString stringWithFormat:@"telprompt://%@",@"18150830596"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneStr]];
iOS 10以后
NSString *phoneStr = [NSString stringWithFormat:@"telprompt://%@",@"18150830596"];
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:phoneStr]
options:@{}
completionHandler:^(BOOL success) {
NSLog(@"success");
}];