ios - 使用 -ObjC/-all_load 链接器标志时找不到符号

Question

更新到 Xcode6 后，我在 IOS 7 上遇到此代码崩溃并显示“找不到符号:_OBJC_CLASS_$_UIUserNotificationSettings”，任何人都可以帮助解决它

if ([application respondsToSelector:@selector(registerUserNotificationSettings:)]){
    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:  (UIUserNotificationTypeSound | UIUserNotificationTypeBadge | UIUserNotificationTypeAlert) categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
    [[UIApplication sharedApplication] registerForRemoteNotifications];
}
else {
    int notifyType = (UIRemoteNotificationTypeAlert |
                      UIRemoteNotificationTypeBadge |
                      UIRemoteNotificationTypeSound);
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:(UIRemoteNotificationType)notifyType];
}

编辑:大家好，这是运行时崩溃，而不是编译时链接错误，

异常类型:EXC_BREAKPOINT (SIGTRAP)异常代码:0x0000000000000001、0x00000000e7ffdefe由线程触发:0

Dyld 错误信息: 找不到符号:_OBJC_CLASS_$_UIUserNotificationSettings

我使用的是 Xcode 6.0 (6A313)，所以我不应该使用任何 #if 来指示 iOS 版本。这段代码在 IOS 8 模拟器上运行良好，但在 IOS 7 设备上崩溃

编辑 2:

最后，这个问题被这些代码解决了，我在下面标记了正确的答案，感谢trojanfoe。

    if ([application respondsToSelector:@selector(registerUserNotificationSettings:)])
{
    Class userNotifyClass = NSClassFromString(@"UIUserNotificationSettings");
    if(userNotifyClass != nil)
    {
        id notifyInstance = [userNotifyClass settingsForTypes:(UIUserNotificationTypeBadge | UIUserNotificationTypeAlert | UIUserNotificationTypeSound) categories:nil];
        [application registerUserNotificationSettings:notifyInstance];
        [application registerForRemoteNotifications];
    }
}
else
{
    int notifyType = (UIRemoteNotificationTypeAlert |
                      UIRemoteNotificationTypeBadge |
                      UIRemoteNotificationTypeSound);
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:(UIRemoteNotificationType)notifyType];
}

Answer 1

我认为您正在使用“基础 SDK”7.x 构建您的项目所以您可以将其更改为 8.0 或在编译期间检查当前版本:

#if __IPHONE_OS_VERSION_MAX_ALLOWED > __IPHONE_7_1       

    UIUserNotificationSettings *settings = [UIUserNotificationSettings settingsForTypes:  (UIUserNotificationTypeSound | UIUserNotificationTypeBadge | UIUserNotificationTypeAlert) categories:nil];
    [[UIApplication sharedApplication] registerUserNotificationSettings:settings];
    [[UIApplication sharedApplication] registerForRemoteNotifications];
#else
    int notifyType = (UIRemoteNotificationTypeAlert |
                      UIRemoteNotificationTypeBadge |
                      UIRemoteNotificationTypeSound);
    [[UIApplication sharedApplication] registerForRemoteNotificationTypes:(UIRemoteNotificationType)notifyType];
#endif