We in the Apple-platform space suffer from a lack of diversity in our conferences. I’ve seen this vastly improve in the US, but over here in Europe it still seems fairly bad. Every month I hear about a new conference which promotes their all-white and often all-male speaker lineup. They often brag about diversity because some women are among their speakers, but their lineups do not represent our community and it makes me sad. Here in Amsterdam, some 49.5% of people have "foreign ancestry" (which is a funny term if you ask me). In just the Netherlands, there are people of all kinds of shades of brown. Throughout history, the Netherlands has invited groups of people from Jamaica, Curaçao, Morocco and so on to live here. Anyone who thinks any country in Europe is all-white is simply ignoring statistics. Every other European country has similar history, people of all shades have been all over Europe as far back as anyone knows.
Now if you organize a conference, you’re taking on quite a bit of risk and work (hopefully not completely alone). There’s a lot to organize and you may even do all that work to find that nobody bought a ticket. It confuses me then why a person or group would volunteer for such a challenge, but then claim that finding an actually-diverse speaker lineup is too hard. If you sold tickets to a conference, but failed to book the venue, you have failed to organize a conference. If you present a speaker lineup that is all white or even worse all male, then I think you have similarly failed.
If you host an open call for papers, many conferences have had improved success by anonymizing proposals to help prevent automatic biases, but also consider where you talk about your CFP. If only your friends hear about it, you won't get quite the variety of submissions you might hope for. IIf this happens, you need to do something else. Simply saying "Well, no women submitted a proposal, so I guess we'll have no women." is a lazy excuse.
If you're not hosting an open call, but inviting speakers directly, make sure to invite people beyond your immediate circle of colleagues/programmer-friends. Last year I was invited to speak at a small first-time conference in Cluj, Romania and I did not know anyone inolved in the conference. They blindly reached out to developers from across Europe hoping to find people who would come and speak. Somehow they managed to find people who were not all white males (or all young/single people even). If these (super cool) inexperienced people can work it out, surely you can too! We're all smart, problem-solving people in this industry, right?
I've also spoken at trySwift in Tokyo. They are an excellent example of diverse lineups. Scroll down this list of previous speakers there and admire all the colors, backgrounds, and experiences represented there!
Also, organizers: when someone brings up these concerns to you who isn’t a co-organizer of your conference, it is not ok to turn to them and reply, “well can you recommend a diverse person we can invite?” This allows you the organizer to sound like you care about solving the problem while pushing the actual work of solving this problem off onto someone who’s job is not organizing a conference. Especially if your conference is the sort that specifically invites speakers rather than hosting a call for papers, it is your job to invite a good group of people, not the underrepresented people who raise their concerns.