Fix some compiler warnings

* explicit optional usage in strings
* remove some unused StringUtil code
* swiftlint affected files
* more concise optional casting (and avoid a `!`)

Compiler warnings: 343 -> 318

(Actually most of these are in external libs, but 115 remain in Signal/SSK)

// FREEBIE

Signal/src/Jobs/MessageFetcherJob.swift

@@ -188,7 +188,7 @@ class MessageFetcherJob: NSObject {
                                             Logger.debug("\(self.TAG) acknowledged delivery for message at timestamp: \(envelope.timestamp)")
         },
                                         failure: { (_: URLSessionDataTask?, error: Error?) in
-                                            Logger.debug("\(self.TAG) acknowledging delivery for message at timestamp: \(envelope.timestamp) failed with error: \(error)")
+                                            Logger.debug("\(self.TAG) acknowledging delivery for message at timestamp: \(envelope.timestamp) failed with error: \(String(describing: error))")
         })
     }
 }

Signal/src/Models/CompareSafetyNumbersActivity.swift

@@ -1,5 +1,6 @@
-//  Created by Michael Kirk on 11/15/16.
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
 
 import Foundation
 
@@ -7,8 +8,8 @@ let CompareSafetyNumbersActivityType = "org.whispersystems.signal.activity.Compa
 
 @objc(OWSCompareSafetyNumbersActivityDelegate)
 protocol CompareSafetyNumbersActivityDelegate {
-    func compareSafetyNumbersActivitySucceeded(activity: CompareSafetyNumbersActivity) -> Void;
-    func compareSafetyNumbersActivity(_ activity: CompareSafetyNumbersActivity, failedWithError error: Error) -> Void;
+    func compareSafetyNumbersActivitySucceeded(activity: CompareSafetyNumbersActivity)
+    func compareSafetyNumbersActivity(_ activity: CompareSafetyNumbersActivity, failedWithError error: Error)
 }
 
 @objc (OWSCompareSafetyNumbersActivity)
@@ -59,7 +60,7 @@ class CompareSafetyNumbersActivity: UIActivity {
 
         let pasteboardString = numericOnly(string: UIPasteboard.general.string)
         guard (pasteboardString != nil && pasteboardString!.characters.count == 60) else {
-            Logger.warn("\(TAG) no valid safety numbers found in pasteboard: \(pasteboardString)")
+            Logger.warn("\(TAG) no valid safety numbers found in pasteboard: \(String(describing: pasteboardString))")
             let error = OWSErrorWithCodeDescription(OWSErrorCode.userError,
                                                     NSLocalizedString("PRIVACY_VERIFICATION_FAILED_NO_SAFETY_NUMBERS_IN_CLIPBOARD", comment: "Alert body for user error"))
 
@@ -70,10 +71,10 @@ class CompareSafetyNumbersActivity: UIActivity {
         let pasteboardSafetyNumbers = pasteboardString!
 
         if pasteboardSafetyNumbers == mySafetyNumbers {
-            Logger.info("\(TAG) successfully matched safety numbers. local numbers: \(mySafetyNumbers) pasteboard:\(pasteboardSafetyNumbers)")
+            Logger.info("\(TAG) successfully matched safety numbers. local numbers: \(String(describing: mySafetyNumbers)) pasteboard:\(pasteboardSafetyNumbers)")
             delegate.compareSafetyNumbersActivitySucceeded(activity:self)
         } else {
-            Logger.warn("\(TAG) local numbers: \(mySafetyNumbers) didn't match pasteboard:\(pasteboardSafetyNumbers)")
+            Logger.warn("\(TAG) local numbers: \(String(describing: mySafetyNumbers)) didn't match pasteboard:\(pasteboardSafetyNumbers)")
             let error = OWSErrorWithCodeDescription(OWSErrorCode.privacyVerificationFailure,
                                                     NSLocalizedString("PRIVACY_VERIFICATION_FAILED_MISMATCHED_SAFETY_NUMBERS_IN_CLIPBOARD", comment: "Alert body"))
             delegate.compareSafetyNumbersActivity(self, failedWithError: error)

Signal/src/ViewControllers/CallViewController.swift

@@ -868,10 +868,8 @@ class CallViewController: UIViewController, CallObserver, CallServiceObserver, R
 
         self.localVideoTrack = localVideoTrack
 
-        var source: RTCAVFoundationVideoSource?
-        if localVideoTrack?.source is RTCAVFoundationVideoSource {
-            source = localVideoTrack?.source as! RTCAVFoundationVideoSource
-        }
+        let source = localVideoTrack?.source as? RTCAVFoundationVideoSource
+
         localVideoView.captureSession = source?.captureSession
         let isHidden = source == nil
         Logger.info("\(TAG) \(#function) isHidden: \(isHidden)")

Signal/src/ViewControllers/ContactsPicker.swift

@@ -347,7 +347,7 @@ fileprivate extension CNContact {
     @objc var nameForCollating: String {
         get {
             if self.familyName.isEmpty && self.givenName.isEmpty {
-                return self.emailAddresses.first?.value as? String ?? ""
+                return self.emailAddresses.first?.value as String? ?? ""
             }
 
             let compositeName: String

Signal/src/ViewControllers/SignalAttachment.swift

@@ -80,7 +80,7 @@ class SignalAttachment: NSObject {
             AssertIsOnMainThread()
 
             assert(oldValue == nil)
-            Logger.verbose("\(SignalAttachment.TAG) Attachment has error: \(error)")
+            Logger.verbose("\(SignalAttachment.TAG) Attachment has error: \(String(describing: error))")
         }
     }
 

Signal/src/call/CallAudioService.swift

@@ -308,7 +308,7 @@ import AVFoundation
                 Logger.debug("\(self.TAG) set category: \(category) options: \(options)")
             }
         } catch {
-            let message = "\(self.TAG) in \(#function) failed to set category: \(category) mode: \(mode), options: \(options) with error: \(error)"
+            let message = "\(self.TAG) in \(#function) failed to set category: \(category) mode: \(String(describing: mode)), options: \(options) with error: \(error)"
             assertionFailure(message)
             Logger.error(message)
         }

Signal/src/call/CallService.swift

@@ -125,7 +125,7 @@ protocol CallServiceObserver: class {
         didSet {
             AssertIsOnMainThread()
 
-            Logger.debug("\(self.TAG) .peerConnectionClient setter: \(oldValue != nil) -> \(peerConnectionClient != nil) \(peerConnectionClient)")
+            Logger.debug("\(self.TAG) .peerConnectionClient setter: \(oldValue != nil) -> \(peerConnectionClient != nil) \(String(describing: peerConnectionClient))")
         }
     }
 
@@ -141,7 +141,7 @@ protocol CallServiceObserver: class {
             updateIsVideoEnabled()
             updateLockTimerEnabling()
 
-            Logger.debug("\(self.TAG) .call setter: \(oldValue != nil) -> \(call != nil) \(call)")
+            Logger.debug("\(self.TAG) .call setter: \(oldValue != nil) -> \(call != nil) \(String(describing: call))")
 
             for observer in observers {
                 observer.value?.didUpdateCall(call:call)
@@ -688,7 +688,7 @@ protocol CallServiceObserver: class {
         guard thread.contactIdentifier() == self.thread?.contactIdentifier() else {
             // This can safely be ignored.
             // We don't want to fail the current call because an old call was slow to send us the hangup message.
-            Logger.warn("\(TAG) ignoring hangup for thread:\(thread) which is not the current thread: \(self.thread)")
+            Logger.warn("\(TAG) ignoring hangup for thread:\(thread) which is not the current thread: \(String(describing: self.thread))")
             return
         }
 

Signal/src/util/StringUtil.h

@@ -1,3 +1,7 @@
+//
+//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//
+
 #import <Foundation/Foundation.h>
 
 @interface NSString (Util)
@@ -11,11 +15,9 @@
 - (NSString *)withMatchesAgainst:(NSRegularExpression *)regex replacedBy:(NSString *)replacement;
 - (bool)containsAnyMatches:(NSRegularExpression *)regex;
 - (NSString *)withPrefixRemovedElseNull:(NSString *)prefix;
-- (NSData *)decodedAsJsonIntoData;
+
 - (NSDictionary *)decodedAsJsonIntoDictionary;
-- (NSData *)decodedAsHexString;
-- (NSData *)decodedAsSpaceSeparatedHexString;
-- (NSData *)decodedAsBase64Data;
+
 - (NSNumber *)tryParseAsDecimalNumber;
 - (NSNumber *)tryParseAsUnsignedInteger;
 - (NSString *)removeAllCharactersIn:(NSCharacterSet *)characterSet;

Signal/src/util/StringUtil.m

@@ -6,20 +6,7 @@
 #import "StringUtil.h"
 
 @implementation NSString (Util)
-- (NSData *)decodedAsHexString {
-    ows_require(self.length % 2 == 0);
 
-    NSUInteger n = self.length / 2;
-    uint8_t result[n];
-    for (NSUInteger i = 0; i < n; i++) {
-        unsigned int r;
-        NSScanner *scanner = [NSScanner scannerWithString:[self substringWithRange:NSMakeRange(i * 2, 2)]];
-        checkOperation([scanner scanHexInt:&r]);
-        checkOperation(r < 256);
-        result[i] = (uint8_t)r;
-    }
-    return [NSData dataWithBytes:result length:sizeof(result)];
-}
 - (NSData *)encodedAsUtf8 {
     NSData *result = [self dataUsingEncoding:NSUTF8StringEncoding];
     checkOperationDescribe(result != nil, @"Not a UTF8 string.");
@@ -54,13 +41,6 @@
         return nil;
     return [self substringFromIndex:prefix.length];
 }
-- (NSData *)decodedAsJsonIntoData {
-    NSError *jsonParseError = nil;
-    id parsedJson = [NSJSONSerialization dataWithJSONObject:self.encodedAsUtf8 options:0 error:&jsonParseError];
-    checkOperationDescribe(jsonParseError == nil, ([NSString stringWithFormat:@"Invalid json: %@", self]));
-    checkOperationDescribe([parsedJson isKindOfClass:NSData.class], @"Unexpected json data");
-    return parsedJson;
-}
 - (NSDictionary *)decodedAsJsonIntoDictionary {
     NSError *jsonParseError = nil;
     id parsedJson = [NSJSONSerialization JSONObjectWithData:self.encodedAsUtf8 options:0 error:&jsonParseError];