如果你不介意使用私有方法，你可以试试下面的代码。

- (void)lc_setAlternateIconName:(NSString*)iconName
{
    //anti apple private method call analyse
    if ([[UIApplication sharedApplication] respondsToSelector:@selector(supportsAlternateIcons)] && 
        [[UIApplication sharedApplication] supportsAlternateIcons])
    {
        NSMutableString *selectorString = [[NSMutableString alloc] initWithCapacity:40];
        [selectorString appendString:@"_setAlternate"];
        [selectorString appendString:@"IconName:"];
        [selectorString appendString:@"completionHandler:"];

        SEL selector = NSSelectorFromString(selectorString);
        IMP imp = [[UIApplication sharedApplication] methodForSelector:selector];
        void (*func)(id, SEL, id, id) = (void *)imp;
        if (func)
        {
            func([UIApplication sharedApplication], selector, iconName, ^(NSError * _Nullable error) {});
        }
    }
}

添加到Andrew's斯威夫特5重写Robert's答案（因为我没有评论的声誉）。
对于默认图标，我们需要传递nil，因此iconName应该是可选的。

func setApplicationIconName(_ iconName: String?) {
        if UIApplication.shared.responds(to: #selector(getter: UIApplication.supportsAlternateIcons)) && UIApplication.shared.supportsAlternateIcons {
            
            typealias setAlternateIconName = @convention(c) (NSObject, Selector, NSString?, @escaping (NSError) -> ()) -> ()
            
            let selectorString = "_setAlternateIconName:completionHandler:"
            
            let selector = NSSelectorFromString(selectorString)
            let imp = UIApplication.shared.method(for: selector)
            let method = unsafeBitCast(imp, to: setAlternateIconName.self)
            method(UIApplication.shared, selector, iconName as NSString?, { _ in })
        }
    }

在Swift中重写了Robert的答案。应用程序也没有被拒绝。

func setApplicationIconName(_ iconName: String) {
        if UIApplication.shared.responds(to: #selector(getter: UIApplication.supportsAlternateIcons)) && UIApplication.shared.supportsAlternateIcons {
            
            typealias setAlternateIconName = @convention(c) (NSObject, Selector, NSString, @escaping (NSError) -> ()) -> ()
            
            let selectorString = "_setAlternateIconName:completionHandler:"
            
            let selector = NSSelectorFromString(selectorString)
            let imp = UIApplication.shared.method(for: selector)
            let method = unsafeBitCast(imp, to: setAlternateIconName.self)
            method(UIApplication.shared, selector, iconName as NSString, { _ in })
        }
    }

根据以上Robert的答案

- (void)lc_setAlternateIconName:(NSString*)iconName
{
    //anti apple private method call analyse
    if ([[UIApplication sharedApplication] respondsToSelector:@selector(supportsAlternateIcons)] && 
        [[UIApplication sharedApplication] supportsAlternateIcons])
    {
        NSMutableString *selectorString = [[NSMutableString alloc] initWithCapacity:40];
        [selectorString appendString:@"_setAlternate"];
        [selectorString appendString:@"IconName:"];
        [selectorString appendString:@"completionHandler:"];

        SEL selector = NSSelectorFromString(selectorString);
        IMP imp = [[UIApplication sharedApplication] methodForSelector:selector];
        void (*func)(id, SEL, id, id) = (void *)imp;
        if (func)
        {
            func([UIApplication sharedApplication], selector, iconName, ^(NSError * _Nullable error) {});
        }
    }
}

我排不上队

void (*func)(id, SEL, id, id) = (void *)imp;

对我来说必须如此

void (*func)(id, SEL, id, id) = (void (*)(id, SEL, id, id))imp;