10拨打系统电话发现弹出框会延迟2s左右出现，很不爽，研究了一下，发现是openURL在iOS 10及其之后会阻塞主线程。所以，拨打电话前，做个判断，来代码,

方案一

// 拨打电话  
+ (void)callPhone:(NSString *)phoneNum {  
      
    if (phoneNum.length == 0) {  
        return;  
    }  
    NSString *callPhone = [NSString stringWithFormat:@"telprompt://%@", phoneNum];  
    NSComparisonResult compare = [[UIDevice currentDevice].systemVersion compare:@"10.0"];  
    if (compare == NSOrderedDescending || compare == NSOrderedSame) {  
        /// 大于等于10.0系统使用此openURL方法  
        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:callPhone] options:@{} completionHandler:nil];  
    } else {  
        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:callPhone]];  
    }  
} 

方案二

// 拨打电话  
+ (void)callPhone:(NSString *)phoneNum {  
      
    if (phoneNum.length == 0) {  
        return;  
    }  
    NSString *callPhone = [NSString stringWithFormat:@"telprompt://%@", phoneNum];  
    dispatch_async(dispatch_get_global_queue(0, 0), ^{  
        [[UIApplication sharedApplication] openURL:[NSURL URLWithString:callPhone]];  
    });  
}