swift 3 - ios : convert anyObject to string
Here's three options for you:
Option 1 - if let
if let b = a as? String {
print(b) // Was a string
} else {
print("Error") // Was not a string
}
Option 2 - guard let
guard let b = a as? String
else {
print("Error") // Was not a string
return // needs a return or break here
}
print(b) // Was a string
Option 3 - let with ?? (null coalescing operator)
let b = a as? String ?? ""
print(b) // Print a blank string if a was not a string
Here's a simple function (repl.it) that will mash any value into a string, with nil
becoming an empty string. I found it useful for dealing with JSON that inconsistently uses null
, blank, numbers, and numeric strings for IDs.
import Foundation
func toString(_ value: Any?) -> String {
return String(describing: value ?? "")
}
let d: NSDictionary = [
"i" : 42,
"s" : "Hello, World!"
]
dump(toString(d["i"]))
dump(toString(d["s"]))
dump(toString(d["x"]))
Prints:
- "42"
- "Hello, World!"
- ""
The compiler suggests that you replace your code with:
let s = String(describing: str)
One other option is available if you have a situation where you want to silently fail with an empty string rather than store something that might not originally be a string as a string.
let s = str as? String ?? ""
else you have the ways of identifying and throwing an error in the answers above/below.
Try
let a = "Test" as AnyObject
guard let b = a as? String else { // Something went wrong handle it here }
print(b) // Test