Question: Is it possible to change a setting, property, etc in Swift for iOS so that it assumes degrees for trigonometry calculations rather than radians?

For example `sin(90)` would be evaluated to `1`.

I have:

```
let pi = 3.14 
var r2d = 180.0/pi
var d2r = pi/180

```

... but the conversions are getting really involved for some of the long trig equations.

Answer: 
There's no setting or property to change the built-in trigonometric functions. You should just work strictly in radians if you want to simplify your expressions, or define your own `sindeg`, `cosdeg`, etc.

Each of the floating-point types has a built-in `static` member named `pi` whose value is the best approximation to π. For example: `Double.pi`, `Float.pi`, `CGFloat.pi`.

Also, sin 90˚ is 1, not 0.
I'm not entirely sure why you'd want to overload the default global method, but if you must, you can provide an alternate method signature:

```
func sin(#degrees: Double) -> Double { // Require a parameter name for method call
    let radians: Double = degrees * (M_PI / 180) // Convert to rad
    return sin(radians) // Return result of default method call with automatic conversion
}

sin(degrees: 90) // 1.0
sin(degrees: 180) // 0.0

```

However, this is really an odd way of doing it, and it would make more sense to explicitly define your own method (that's what they're for), in a similar way:

```
func sinFromDegrees(degrees: Double) -> Double {
    let radians: Double = degrees * (M_PI / 180)
    return sin(radians)
}

sinFromDegrees(90) // 1.0
sinFromDegrees(180) // 0.0

```