1 files changed, 115 insertions, 0 deletions
diff --git a/MASShortcutView+UserDefaults.m b/MASShortcutView+UserDefaults.m
new file mode 100644
index 0000000..133453e
--- /dev/null
+++ b/MASShortcutView+UserDefaults.m
@@ -0,0 +1,115 @@
+#import "MASShortcutView+UserDefaults.h"
+#import "MASShortcut.h"
+#import <objc/runtime.h>
+
+@interface MASShortcutDefaultsObserver : NSObject
+
+@property (nonatomic, readonly) NSString *userDefaultsKey;
+@property (nonatomic, readonly, weak) MASShortcutView *shortcutView;
+
+- (id)initWithShortcutView:(MASShortcutView *)shortcutView userDefaultsKey:(NSString *)userDefaultsKey;
+
+@end
+
+#pragma mark -
+
+@implementation MASShortcutView (UserDefaults)
+
+void *kDefaultsObserver = &kDefaultsObserver;
+
+- (NSString *)associatedUserDefaultsKey
+{
+    MASShortcutDefaultsObserver *defaultsObserver = objc_getAssociatedObject(self, kDefaultsObserver);
+    return defaultsObserver.userDefaultsKey;
+}
+
+- (void)setAssociatedUserDefaultsKey:(NSString *)associatedUserDefaultsKey
+{
+    MASShortcutDefaultsObserver *defaultsObserver = [[MASShortcutDefaultsObserver alloc] initWithShortcutView:self userDefaultsKey:associatedUserDefaultsKey];
+    objc_setAssociatedObject(self, kDefaultsObserver, defaultsObserver, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
+}
+
+@end
+
+#pragma mark -
+
+@implementation MASShortcutDefaultsObserver {
+    MASShortcut *_originalShortcut;
+    BOOL _internalPreferenceChange;
+    BOOL _internalShortcutChange;
+}
+
+- (id)initWithShortcutView:(MASShortcutView *)shortcutView userDefaultsKey:(NSString *)userDefaultsKey
+{
+    self = [super init];
+    if (self) {
+        _originalShortcut = shortcutView.shortcutValue;
+        _shortcutView = shortcutView;
+        _userDefaultsKey = userDefaultsKey.copy;
+        [self startObservingShortcutView];
+    }
+    return self;
+}
+
+- (void)dealloc
+{
+    // __weak _shortcutView is not yet deallocated because it refers MASShortcutDefaultsObserver
+    [self stopObservingShortcutView];
+}
+
+#pragma mark -
+
+void *kShortcutValueObserver = &kShortcutValueObserver;
+
+- (void)startObservingShortcutView
+{
+    // Read initial shortcut value from user preferences
+    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
+    NSData *data = [defaults dataForKey:_userDefaultsKey];
+    _shortcutView.shortcutValue = [MASShortcut shortcutWithData:data];
+
+    // Observe user preferences to update shortcut value when it changed
+    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(userDefaultsDidChange:) name:NSUserDefaultsDidChangeNotification object:defaults];
+
+    // Observe the keyboard shortcut that user inputs by hand
+    [_shortcutView addObserver:self forKeyPath:@"shortcutValue" options:0 context:kShortcutValueObserver];
+}
+
+- (void)userDefaultsDidChange:(NSNotification *)note
+{
+    // Ignore notifications posted from -[self observeValueForKeyPath:]
+    if (_internalPreferenceChange) return;
+
+    _internalShortcutChange = YES;
+    NSData *data = [note.object dataForKey:_userDefaultsKey];
+    _shortcutView.shortcutValue = [MASShortcut shortcutWithData:data];
+    _internalShortcutChange = NO;
+}
+
+- (void)stopObservingShortcutView
+{
+    // Stop observing keyboard hotkeys entered by user in the shortcut view
+    [_shortcutView removeObserver:self forKeyPath:@"shortcutValue" context:kShortcutValueObserver];
+
+    // Stop observing user preferences
+    [[NSNotificationCenter defaultCenter] removeObserver:self name:NSUserDefaultsDidChangeNotification object:[NSUserDefaults standardUserDefaults]];
+
+    // Restore original hotkey in the shortcut view
+    _shortcutView.shortcutValue = _originalShortcut;
+}
+
+- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
+{
+    if (context == kShortcutValueObserver) {
+        if (_internalShortcutChange) return;
+        MASShortcut *shortcut = [object valueForKey:keyPath];
+        _internalPreferenceChange = YES;
+        [[NSUserDefaults standardUserDefaults] setObject:shortcut.data forKey:_userDefaultsKey];
+        _internalPreferenceChange = NO;
+    }
+    else {
+        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
+    }
+}
+
+@end