Lock publick methods to prevent concurrency issues

Demo/Base.lproj/LaunchScreen.xib

@@ -15,14 +15,14 @@
             <rect key="frame" x="0.0" y="0.0" width="480" height="480"/>
             <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
             <subviews>
-                <label opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" misplaced="YES" text="No rights reserved." textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" minimumFontSize="9" translatesAutoresizingMaskIntoConstraints="NO" id="8ie-xW-0ye">
-                    <rect key="frame" x="20" y="439" width="441" height="21"/>
+                <label opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="No rights reserved." textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" minimumFontSize="9" translatesAutoresizingMaskIntoConstraints="NO" id="8ie-xW-0ye">
+                    <rect key="frame" x="20" y="439" width="440" height="21"/>
                     <fontDescription key="fontDescription" type="system" pointSize="17"/>
                     <color key="textColor" cocoaTouchSystemColor="darkTextColor"/>
                     <nil key="highlightedColor"/>
                 </label>
-                <label opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" misplaced="YES" text="Keychain Swift" textAlignment="center" lineBreakMode="middleTruncation" baselineAdjustment="alignBaselines" minimumFontSize="18" translatesAutoresizingMaskIntoConstraints="NO" id="kId-c2-rCX">
-                    <rect key="frame" x="20" y="140" width="441" height="43"/>
+                <label opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Keychain Swift" textAlignment="center" lineBreakMode="middleTruncation" baselineAdjustment="alignBaselines" minimumFontSize="18" translatesAutoresizingMaskIntoConstraints="NO" id="kId-c2-rCX">
+                    <rect key="frame" x="20" y="139.5" width="440" height="43"/>
                     <fontDescription key="fontDescription" type="boldSystem" pointSize="36"/>
                     <color key="textColor" cocoaTouchSystemColor="darkTextColor"/>
                     <nil key="highlightedColor"/>

Sources/KeychainSwift.swift

@@ -234,7 +234,7 @@ open class KeychainSwift {
   
   /**
    
-  Same as delete but is only accessed internally, since it is not thread safe.
+  Same as `delete` but is only accessed internally, since it is not thread safe.
    
    - parameter key: The key that is used to delete the keychain item.
    - returns: True if the item was successfully deleted.