iOS开发 iOS 10拨打系统电话，弹出框延迟出现问题

iOS 10拨打系统电话发现弹出框会延迟2s左右出现，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,

// 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]];  
}  
} 

// 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]];  
});  
}