ios - NSInvalidArgumentException，原因 : '-[NSNull isEqualToString:]

Question

我收到推送通知并尝试按如下方式解析字典，但出现以下异常。

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSNull isEqualToString:]: unrecognized selector sent to instance 0x1a6574ef8'

这是我收到的字典

实现

-(void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
{
    if (application.applicationState == UIApplicationStateActive)
    {
       // exception happens the following line
        if([[userInfo objectForKey:@"aps"] objectForKey:@"alert"] != NULL && 
           [[[userInfo objectForKey:@"aps"] objectForKey:@"alert"]isEqualToString:@"New Order!"])
        {
            [[NSNotificationCenter defaultCenter] postNotificationName: @"newOrderNotificationMessage" object: [userInfo objectForKey:@"aps"]];
        }
}

Answer 1

你还需要检查 NSNull 类，试试这个

-(void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
{
    if (application.applicationState == UIApplicationStateActive)
    {
        // exception happens the following line
        if([[userInfo objectForKey:@"aps"] objectForKey:@"alert"] != NULL && [[[userInfo objectForKey:@"aps"] objectForKey:@"alert"] class] != [NSNull class]){
            if ([[[userInfo objectForKey:@"aps"] objectForKey:@"alert"]isEqualToString:@"New Order!"])
            {
                [[NSNotificationCenter defaultCenter] postNotificationName: @"newOrderNotificationMessage" object: [userInfo objectForKey:@"aps"]];
            }
        }

    }
}

希望对你有帮助