Hi all! I’m quite new to DnD, so I’m just looking for some guidance :)

I have picked up the “True Strike” Cantrip on my Warlock, and notice that it has a range of Self. I’ve got Pact of the Blade, and I’ve chosen Whip as my weapon of choice. The Whip has a 10ft range for combat. So, when I cast True Strike, is the range Self or 10ft? Does it depend on my weapon? And is it a Cantrip that I can pair Eldritch Spar with?

"Range: Self" means the spells originates from the caster. The range of the attack is the range of the weapon.

Since the range of the spell is "self" it is not eligible for Eldritch Spear.

If you throw the whip, you do not get the true strike damage, if you hold on to the end and hit with the tip, you get the damage.

True Strike can be used with Ranged or Thrown weapons just fine. If you throw a whip, it'll almost certainly count as an improvised weapon. (True Strike doesn't make it not-improvised, though, so no proficiency bonus to hit and the die is 1d4...)

Quote from succuboys >>

Hi all! I’m quite new to DnD, so I’m just looking for some guidance :)

I have picked up the “True Strike” Cantrip on my Warlock, and notice that it has a range of Self. I’ve got Pact of the Blade, and I’ve chosen Whip as my weapon of choice. The Whip has a 10ft range for combat. So, when I cast True Strike, is the range Self or 10ft? Does it depend on my weapon? And is it a Cantrip that I can pair Eldritch Spar with?

One other thing that's worth pointing out, in addition to what kenclary said, is that True Strike is not super useful for Warlocks with Pact of the Blade, because Pact of the Blade already provides most of the benefits of using True Strike (letting you use Charisma for the attack and damage rolls, and giving it a better damage type). Until you reach level 5 (where True Strike provides a damage bonus too) you're not gaining anything over just making a normal attack. And once you reach level 5, you may be better off taking the Eldritch Invocations that let you make multiple attacks with your Pact weapon instead.

True Strike is more useful for spellcaster characters who want to use weapons but don't already have something like Pact of the Blade to make it easier.

Quote from kenclary >>

True Strike can be used with Ranged or Thrown weapons just fine. If you throw a whip, it'll almost certainly count as an improvised weapon. (True Strike doesn't make it not-improvised, though, so no proficiency bonus to hit and the die is 1d4...)

Would True Strike even work at all for throwing a whip if you don't have Proficiency with Improvised Weapons? 

One of the requirements of True Strike's components is that you have Proficiency with the weapon.

Since the original character had Pact of the Blade, so the relatively-easy End-run is "I conjure a throwable whip, " but then there's also "I conjure an actual weapon meant for throwing."  in that situation.

That said, I kind of think True Strike doesn't have much to offer to a  Single-Classed Warlock with Pact of the Blade as a general cantrip, especially since Warlocks don't get that many Cantrip choices to begin with.