Minor edits

2013-08-19-nshashtable-and-nsmaptable.md

@@ -35,9 +35,8 @@ hashTable.addObject("foo")
 hashTable.addObject("bar")
 hashTable.addObject(42)
 hashTable.removeObject("bar")
-print(hashTable.allObjects)
+print("Members: \(hashTable.allObjects)")
 ~~~
-
 ~~~{objective-c}
 NSHashTable *hashTable = [NSHashTable hashTableWithOptions:NSPointerFunctionsCopyIn];
 [hashTable addObject:@"foo"];
@@ -65,17 +64,19 @@ NSLog(@"Members: %@", [hashTable allObjects]);
 - `NSMapTable` can `copy` its values on input.
 - `NSMapTable` can contain arbitrary pointers, and use pointer identity for equality and hashing checks.
 
+> *Note:* `NSMapTable`'s focus on strong and weak references means that Swift's prevalent value types are a no go—reference types only, please.
+
 ### Usage
 
 Instances where one might use `NSMapTable` include non-copyable keys and storing weak references to keyed delegates or another kind of weak object.
 
 ~~~{swift}
 let delegate: AnyObject = ...
 let mapTable = NSMapTable(keyOptions: .StrongMemory, valueOptions: .WeakMemory)
+
 mapTable.setObject(delegate, forKey: "foo")
 print("Keys: \(mapTable.keyEnumerator().allObjects)")
 ~~~
-
 ~~~{objective-c}
 id delegate = ...;
 NSMapTable *mapTable = [NSMapTable mapTableWithKeyOptions:NSMapTableStrongMemory
@@ -105,7 +106,11 @@ extension NSMapTable {
         }
 
         set {
-            setObject(newValue, forKey: key)
+            if newValue != nil {
+                setObject(newValue, forKey: key)
+            } else {
+                removeObjectForKey(key)
+            }
         }
     }
 }
@@ -121,7 +126,11 @@ extension NSMapTable {
 
 - (void)setObject:(id)obj forKeyedSubscript:(id)key
 {
-    [self setObject:obj forKey:key];
+    if (obj != nil) {
+        [self setObject:obj forKey:key];
+    } else {
+        [self removeObjectForKey:key];
+    }
 }
 
 @end

2013-09-23-ios7.md

@@ -292,12 +292,7 @@ Even though the number of people who have actually read something saved for late
 import SafariServices
 
 let url = NSURL(string: "http://nshipster.com/ios7")!
-do {
-    try SSReadingList.defaultReadingList()?.addReadingListItemWithURL(url, title: "NSHipster",
-        previewText: "...")
-} catch let error {
-    print("Error: \(error)")
-}
+try? SSReadingList.defaultReadingList()?.addReadingListItemWithURL(url, title: "NSHipster", previewText: "...")
 ~~~
 
 ~~~{objective-c}

2014-06-09-ios8.md

@@ -86,7 +86,7 @@ import CoreMotion
 
 let lengthFormatter = NSLengthFormatter()
 let pedometer = CMPedometer()
-pedometer.startPedometerUpdatesFromDate(NSDate(), withHandler: { data, error in
+pedometer.startPedometerUpdatesFromDate(NSDate()) { data, error in
     if let data = data {
         print("Steps Taken: \(data.numberOfSteps)")
 
@@ -98,7 +98,7 @@ pedometer.startPedometerUpdatesFromDate(NSDate(), withHandler: { data, error in
             print("Speed: \(lengthFormatter.stringFromMeters(speed)) / s")
         }
     }
-})
+}
 ~~~
 
 ## CMAltimeter
@@ -110,11 +110,11 @@ import CoreMotion
 
 let altimeter = CMAltimeter()
 if CMAltimeter.isRelativeAltitudeAvailable() {
-    altimeter.startRelativeAltitudeUpdatesToQueue(NSOperationQueue.mainQueue(), withHandler: { data, error in
+    altimeter.startRelativeAltitudeUpdatesToQueue(NSOperationQueue.mainQueue()) { data, error in
         if let data = data {
             print("Relative Altitude: \(data.relativeAltitude)")
         }
-    })
+    }
 }
 ~~~
 
@@ -149,12 +149,12 @@ The following example shows how statistics summed over the duration of the day c
 ~~~{swift}
 import HealthKit
 
-let collection: HKStatisticsCollection? = nil//...
+let collection: HKStatisticsCollection? = ...
 let statistics: HKStatistics? = collection?.statisticsForDate(NSDate())
 let sources: [HKSource] = statistics?.sources ?? []
 
 for source in sources {
-    if let quantity: HKQuantity = statistics?.sumQuantityForSource(source) {
+    if let quantity = statistics?.sumQuantityForSource(source) {
         if quantity.isCompatibleWithUnit(HKUnit.gramUnitWithMetricPrefix(.Kilo)) {
             let massFormatter = NSMassFormatter()
             let kilograms = quantity.doubleValueForUnit(HKUnit.gramUnitWithMetricPrefix(.Kilo))
@@ -194,11 +194,11 @@ NSStream.getStreamsToHostWithName("nshipster.com",
 
 ## NSString -localizedCaseInsensitiveContainsString
 
-Also filed under: "small but solid fixes", is this convenience method for `NSString`:
+Also filed under: "small but solid fixes", is this convenience method for `String`/`NSString`:
 
 ~~~{swift}
-let string: String = "Café"
-let substring: String = "É"
+let string = "Café"
+let substring = "É"
 
 string.localizedCaseInsensitiveContainsString(substring) // true
 ~~~
@@ -246,15 +246,15 @@ The Foundation URL Loading System has remained relatively unchanged since last y
 import Foundation
 
 let session = NSURLSession()
-let task = session.dataTaskWithURL(NSURL(string: "http://nshipster.com")!, completionHandler: { data, response, error in
+let task = session.dataTaskWithURL(NSURL(string: "http://nshipster.com")!) { data, response, error in
     // ...
-})
+}
 
 let protectionSpace = NSURLProtectionSpace()
 let credentialStorage = NSURLCredentialStorage()
-credentialStorage.getCredentialsForProtectionSpace(protectionSpace, task: task, completionHandler: { credentials in
+credentialStorage.getCredentialsForProtectionSpace(protectionSpace, task: task) { credentials in
     // ...
-})
+}
 ~~~
 
 ## kUTTypeToDoItem
@@ -275,6 +275,23 @@ Most users are completely unaware that most pictures taken with phones these day
 
 New to the Image I/O framework is a convenient new option for `CGImageDestination`: `kCGImageMetadataShouldExcludeGPS`, which does what you'd expect.
 
+~~~{swift}
+import UIKit
+import ImageIO
+import MobileCoreServices
+
+let image = ...
+let fileURL = NSURL(fileURLWithPath: "/path/to/output.jpg")
+let options: NSDictionary = [kCGImageDestinationLossyCompressionQuality as NSString: 0.75,
+                            kCGImageMetadataShouldExcludeGPS as NSString: true]
+
+if let imageDestination = CGImageDestinationCreateWithURL(fileURL, kUTTypeJPEG, 1, nil),
+    let cgImage = image.CGImage
+{
+    CGImageDestinationAddImage(imageDestination, cgImage, options)
+    CGImageDestinationFinalize(imageDestination)
+}
+~~~
 ~~~{objective-c}
 @import UIKit;
 @import ImageIO;
@@ -346,6 +363,22 @@ Imagine: with CloudKit and LocalAuthentication, nearly all of the friction to cr
 
 LocalAuthentication works in terms of an `LAContext` class, which evaluates a specified policy, and gives a thumbs up or thumbs down on user authentication. At no point is any biometric information made available to the application—everything is kept safe on the hardware itself.
 
+~~~{swift}
+let context = LAContext()
+var error: NSError?
+
+if context.canEvaluatePolicy(.DeviceOwnerAuthenticationWithBiometrics, error: &error) {
+    context.evaluatePolicy(.DeviceOwnerAuthenticationWithBiometrics, localizedReason: "...") { success, error in
+        if success {
+            // ...
+        } else {
+            print("Error: \(error)")
+        }
+    }
+} else {
+    print("Error: \(error)")
+}
+~~~
 ~~~{objective-c}
 LAContext *context = [[LAContext alloc] init];
 NSError *error = nil;

2014-11-03-uisplitviewcontroller.md

@@ -82,7 +82,6 @@ override func viewDidLoad() {
     navigationItem.leftItemsSupplementBackButton = true
 }
 ~~~
-
 ~~~{objective-c}
 - (void)viewDidLoad {
     [super viewDidLoad];
@@ -111,13 +110,9 @@ There is one more optimization we can do for the iPhone 6+ via [`UISplitViewCont
 When the user first launches the app, we can make the master view controller fully displayed until the user selects a list item:
 
 ~~~{swift}
-import UIKit
-
 class SelectColorTableViewController: UITableViewController, UISplitViewControllerDelegate {
     private var collapseDetailViewController = true
 
-    // MARK: UITableViewController
-
     override func viewDidLoad() {
         super.viewDidLoad()
 
@@ -126,7 +121,7 @@ class SelectColorTableViewController: UITableViewController, UISplitViewControll
 
     // ...
 
-    // MARK: UITableViewDelegate
+    // MARK: - UITableViewDelegate
 
     override func tableView(tableView: UITableView, didSelectRowAtIndexPath indexPath: NSIndexPath) {
         collapseDetailViewController = false
@@ -139,13 +134,14 @@ class SelectColorTableViewController: UITableViewController, UISplitViewControll
     }
 }
 ~~~
-
 ~~~{objective-c}
-@import UIKit;
+// SelectColorTableViewController.h
 
 @interface SelectColorTableViewController : UITableViewController <UISplitViewControllerDelegate>
 @end
 
+// SelectColorTableViewController.m
+
 @interface SelectColorTableViewController ()
 
 @property (nonatomic) BOOL shouldCollapseDetailViewController;
@@ -154,8 +150,6 @@ class SelectColorTableViewController: UITableViewController, UISplitViewControll
 
 @implementation SelectColorTableViewController
 
-#pragma mark - UITableViewController
-
 - (void)viewDidLoad {
     [super viewDidLoad];