Fix String warnings.

Author: jseibert

Sources/GraphQL/Error/SyntaxError.swift

@@ -28,7 +28,7 @@ func highlightSourceAtLocation(source: Source, location: SourceLocation) -> Stri
     let prevLineNum = (line - 1).description
     let lineNum = line.description
     let nextLineNum = (line + 1).description
-    let padLength = nextLineNum.characters.count
+    let padLength = nextLineNum.count
 
     let lines = splitLines(string: source.body)
 
@@ -73,5 +73,5 @@ func splitLines(string: String) -> [String] {
 }
 
 func leftpad(_ length: Int, _ string: String) -> String {
-    return String(repeating: " ", count: max(length - string.characters.count + 1, 0)) + string
+    return String(repeating: " ", count: max(length - string.count + 1, 0)) + string
 }

Sources/GraphQL/Map/MapCustomStringConvertible.swift

@@ -39,7 +39,7 @@ extension Map {
         func escape(_ source: String) -> String {
             var string = "\""
 
-            for character in source.characters {
+            for character in source {
                 if let escapedSymbol = escapeMapping[character] {
                     string.append(escapedSymbol)
                 } else {

Sources/GraphQL/Utilities/ASTFromValue.swift

@@ -111,7 +111,7 @@ func astFromValue(
 
         // Use JSON stringify, which uses the same string encoding as GraphQL,
         // then remove the quotes.
-        return StringValue(value: String(serialized.description.characters.dropFirst().dropLast()))
+        return StringValue(value: String(serialized.description.dropFirst().dropLast()))
     }
 
     throw GraphQLError(message: "Cannot convert value to AST: \(serialized)")

Tests/GraphQLTests/MapTests/MapTests.swift

@@ -578,7 +578,7 @@ public class MapTests : XCTestCase {
             "string": "foo\nbar",
             ]
 
-        XCTAssertEqual(buffer.debugDescription.characters.count, 465)
+        XCTAssertEqual(buffer.debugDescription.count, 465)
     }
 
 

Tests/GraphQLTests/PersistedQueriesTests/PersistedQueriesTests.swift

@@ -30,7 +30,7 @@ class PersistedQueriesTests: XCTestCase {
         let result = try lookup("parse_error")
         switch result {
         case .parseError(let error):
-            XCTAssertEqual(String(error.message.characters.prefix(57)), "Syntax Error parse_error (1:4) Expected Name, found <EOF>")
+            XCTAssertEqual(String(error.message.prefix(57)), "Syntax Error parse_error (1:4) Expected Name, found <EOF>")
             XCTAssertEqual(error.locations.first?.line, 1)
             XCTAssertEqual(error.locations.first?.column, 4)
             return
@@ -77,7 +77,7 @@ class PersistedQueriesTests: XCTestCase {
         do {
             _ = try graphql(queryRetrieval: self, queryId: "parse_error")
         } catch let error as GraphQLError {
-            XCTAssertEqual(String(error.message.characters.prefix(57)), "Syntax Error parse_error (1:4) Expected Name, found <EOF>")
+            XCTAssertEqual(String(error.message.prefix(57)), "Syntax Error parse_error (1:4) Expected Name, found <EOF>")
             XCTAssertEqual(error.locations.first?.line, 1)
             XCTAssertEqual(error.locations.first?.column, 4)
         }