swizzl dealloc for KVO crash protector

Author: NilStack

.DS_Store

@@ -50,6 +50,7 @@ + (void)load {
     });
 }
 
+// TODO: swizzle observeValueForKeyPath
 - (void)hsAddObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath options:(NSKeyValueObservingOptions)options context:(void *)context {
 
     if(!self.kvoProtector) {
@@ -59,7 +60,7 @@ - (void)hsAddObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath option
 
     NSDictionary *kvoInfo;
     if(context) {
-       kvoInfo = @{@"Observer": observer, @"KeyPath": keyPath, @"Options": [NSNumber numberWithInteger:options], @"Context": (__bridge NSObject *)(context)};
+        kvoInfo = @{@"Observer": observer, @"Observed": self, @"KeyPath": keyPath, @"Options": [NSNumber numberWithInteger:options], @"Context": (__bridge NSObject *)(context)};
     } else {
        kvoInfo = @{@"Observer": observer, @"KeyPath": keyPath, @"Options": [NSNumber numberWithInteger:options]};
     }
@@ -93,7 +94,7 @@ - (void)hsAddObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath option
 - (void)hsRemoveObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath {
 
     if(!self.kvoProtector) {
-        NSLog(@"Error: no observer obserse you.");
+        NSLog(@"Error: no observer observes you.");
         return;
     } else {
         HSKVOProtector *kvoProtector = self.kvoProtector;
@@ -114,18 +115,20 @@ - (void)hsRemoveObserver:(NSObject *)observer forKeyPath:(NSString *)keyPath {
             if (kvoInfoArray.count == 0) {
                 NSMutableDictionary *mutableObserverDict = [observerDict mutableCopy];
                 [mutableObserverDict removeObjectForKey:keyPath];
-                [self removeObserver:kvoProtector forKeyPath:keyPath];
+                [self hsRemoveObserver:kvoProtector forKeyPath:keyPath];
             }
 
         }
     }
 
 }
 
-- (void)hsObserveValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
-    
-    NSLog(@"hsObserveValueForKeyPath");
-    
+- (void)hsDealloc {
+    if(self.kvoProtector) {
+        NSMutableDictionary *mutableObserverDict = [self.kvoProtector.observerDict mutableCopy];
+        [mutableObserverDict removeAllObjects];
+        self.kvoProtector = nil;
+    }
 }
 
 + (void)swizzleAddObserver {
@@ -144,9 +147,10 @@ + (void)swizzleRemoveObserver {
     }
 }
 
-+ (void)swizzleObserveValueForKeyPath {
++ (void)swizzleDealloc {
     NSError *error;
-    BOOL success = [[self class] jr_swizzleMethod:@selector(removeObserver:forKeyPath:) withMethod:@selector(hsObserveValueForKeyPath:ofObject:change:context:) error:&error];
+    const SEL deallocSel  = NSSelectorFromString(@"dealloc");
+    BOOL success = [[self class] jr_swizzleMethod:deallocSel withMethod:@selector(hsDealloc) error:&error];
     if (!success || error) {
         NSLog(@"Can't swizzle methods - %@", [error description]);
     }

HardShell/Source/NSObject+HardShell.m

@@ -35,7 +35,6 @@ - (void)viewDidLoad {
     [label removeObserver:self forKeyPath:@"textColor"];
 
     //label.text = @"new text";
-    
 }
 
 

HardShell/ViewController.m

@@ -4,7 +4,7 @@ HardShell is a protector to keep app from specific crashes. Now it only protects
 
 The idea is from [Baymax's introduction](https://neyoufan.github.io/2017/01/13/ios/BayMax_HTSafetyGuard/) which is from Wangyi (Hangzhou). They promise Baymax SDK will be released but don't mention the schedule and if it will be opensourced. So I build HardShell.
 
-It is still at early stages and not product ready to launch. Please help me to do more testing. Pull requests are always highly welcomed. 
+It is still at early stages and not product ready to launch. Please help me to do more testing. Pull requests are always highly welcomed.
 
 ### unrecognized selector crash
 
@@ -27,6 +27,17 @@ The crash disappeared and the root cause is shown.
 
 <img src="Screenshots/After.png" align="center" height="28" width="400">
 
+### KVO crash
+
+1. add same observer repeatedly for same key path
+2. remove same observation repeatedly
+3. remove nonexistent observation
+For example:
+
+<img src="Screenshots/KVOCode.png" align="center" height="135" width="589">
+
+<img src="Screenshots/KVOLog.png" align="center" height="777" width="404">
+
 Other features will come soon.
 
 ### License