So there are multiple ways to do this.

Random color using swift

Here is one of the way.

What i am doing below is generate 3 random numbers for RGB colour code (Red, Green, Blue) and then generating a UIColor object out of it. Note that UIColor object only expects the colour values to be in decimals between 0 to 1 and so i thought drand48 should be the best way to do. If you think there is a better way let me know.

In the above code i have use the drand48() method to generate a random number between 0 to 1.  These functions generate pseudo-random numbers using the linear congruential algorithm and 48-bit integer arithmetic.To learn more about this method you can refer this page.

Also note that the drand48()  returns a Double value whereas the UIColour init method expects the value to be in CGFloat. I am not sure if there is any alternative to CGFloat for swift but i can use it directly. So i just type casted it to CGFloat.

Other alternative options would be using  arc4random_uniform method and then MOD it to get a decimal value.