fix: balance overflow

Author: reez

BDKSwiftExampleWallet/Extensions/Int+Extensions.swift

@@ -38,22 +38,28 @@ extension UInt64 {
         if self == 0 {
             return "0.00 000 000"
         } else {
-            let balanceString = String(format: "%010d", self)
-
-            let zero = balanceString.prefix(2)
-            let first = balanceString.dropFirst(2).prefix(2)
-            let second = balanceString.dropFirst(4).prefix(3)
-            let third = balanceString.dropFirst(7).prefix(3)
-
-            var formattedZero = zero
-
-            if zero == "00" {
-                formattedZero = zero.dropFirst()
-            } else if zero.hasPrefix("0") {
-                formattedZero = zero.suffix(1)
-            }
-
-            let formattedBalance = "\(formattedZero).\(first) \(second) \(third)"
+            // Convert satoshis to BTC (1 BTC = 100,000,000 sats)
+            let btcValue = Double(self) / 100_000_000.0
+            
+            // Format BTC value to exactly 8 decimal places
+            let btcString = String(format: "%.8f", btcValue)
+            
+            // Split the string at the decimal point
+            let parts = btcString.split(separator: ".")
+            guard parts.count == 2 else { return btcString }
+            
+            let wholePart = String(parts[0])
+            let decimalPart = String(parts[1])
+            
+            // Ensure decimal part is exactly 8 digits
+            let paddedDecimal = decimalPart.padding(toLength: 8, withPad: "0", startingAt: 0)
+            
+            // Format as XX.XX XXX XXX
+            let first = paddedDecimal.prefix(2)
+            let second = paddedDecimal.dropFirst(2).prefix(3)
+            let third = paddedDecimal.dropFirst(5).prefix(3)
+            
+            let formattedBalance = "\(wholePart).\(first) \(second) \(third)"
 
             return formattedBalance
         }