Primitive example on how to manually parse a JSON in Swift

swift.sh

#!/usr/bin/swift

import Foundation 

let jsonData = Data("""
	{
		"premiumBundle": {
			"enabled": true,
			"variations": {
				"sku1": {
					"savings": "60%",
					"sku": "US-PBT0-5-2-1"
				},
				"sku2": {
					"savings": "70%",
					"sku": "US-PBT1-5-2-1"
				},
				"sku3": {
					"savings": "80%",
					"sku": "US-PBT2-5-2-1"
				},
				"sku4": {
					"savings": "90%",
					"sku": "US-PBT3-5-2-1"
				}
			}
		}
	}
	""".utf8)

do {
	if let json = try JSONSerialization.jsonObject(with: jsonData, options: []) as? [String: AnyObject] {
		if let premiumBundle = json["premiumBundle"] as? [String: AnyObject] {
			if let variations = premiumBundle["variations"] as? [String: [String: AnyObject]] {
				if let sku3Variation = variations["sku3"] {
				
					// SKU
					if let sku = sku3Variation["sku"] as? String {
						print(sku)
					}
					
					// SAVINGS
					if let savings = sku3Variation["savings"] as? String {
						print(savings)
					}
				}
			}
		}
	}
} catch {
	print(error)
}

/// Prints:
/// US-PBT2-5-2-1
/// 80%