Can't Unity draw fine and smooth line?

I'm working on drawing lines in Unity, but find there is no way to draw clear, fine and smooth line in Unity, neither LineRenderer nor GL.LINES, both of them got jaggy, pixelated and coarse lines, even set Anti-Aliasing to 8x, just a tiny improvement. But when I turn to see iOS, I find it's easy to draw perfect and smooth line with the original iOS Graphic API, just as the screenshot of Paper app in iOS below, while we can see the screenshot of Unity drawing with LineRenderer, it's really ugly, even use Bezier, still jaggy.

Isn't there any way to draw smooth line in Unity? Will Shader do some great help? Does anyone have a good idea? Very appreciate it.

Paper on iOS

Unity with LineRenderer

• What resolution are you rendering your game in? – Sturlen Nov 2 '17 at 14:32
• @ZEKE, it looks like you've already figured out my problem. Before that I used the Default Is Native Resolution and kept the Low Resolution Aspect Ratios at top of Game view turned on, now I get clear lines. Thank you so much! – Suge Nov 2 '17 at 15:44
• good to hear! Still, I think you should add your fix as an answer, that way others with the same problem can find it more easily. – Sturlen Nov 2 '17 at 16:46
• @ZEKE, yes, I will do that :) – Suge Nov 3 '17 at 0:50

@ZEKE briefly figured out the problem might be wrong settings of game rendering resolution. When I looked into it I found there had been a Low Resolution Aspect Ratios option checked on at top of Unity Game view > Free Aspect, I tried turning off it, then got clear lines.
(Meanwhile, I've also tried changing the Default Is Native Resolution in Player Settings to something like 3000x2000, but it looked none affection to this issue)