Button border color - Objective C - Swift

Question

I want to change my border color to a specific hex color(#21CE99), can you guys please help me?

I\'ve already known how to change it to a basic color, for example:

Answer 1

easier

_button.layer.borderColor = [UIColor colorWithRed:0x21 / 255.0 green:0xce / 255.0 blue:0x99 / 255.0 alpha:1.0].CGColor;