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//
// GTMNSObject+KeyValueObserving.m
//
// Copyright 2009 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy
// of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.
//
//
// MAKVONotificationCenter.m
// MAKVONotificationCenter
//
// Created by Michael Ash on 10/15/08.
//
// This code is based on code by Michael Ash.
// See comment in header.
#import "GTMDefines.h"
#import "GTMNSObject+KeyValueObserving.h"
#import "GTMDefines.h"
#import "GTMDebugSelectorValidation.h"
#import "GTMObjC2Runtime.h"
#import "GTMMethodCheck.h"
// A singleton that works as a dispatch center for KVO
// -[NSObject observeValueForKeyPath:ofObject:change:context:] and turns them
// into selector dispatches. It stores a collection of
// GTMKeyValueObservingHelpers, and keys them via the key generated by
// -dictionaryKeyForObserver:ofObject:forKeyPath:selector.
@interface GTMKeyValueObservingCenter : NSObject {
@private
NSMutableDictionary *observerHelpers_;
}
+ (id)defaultCenter;
- (void)addObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options;
- (void)removeObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector;
- (id)dictionaryKeyForObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector;
@end
@interface GTMKeyValueObservingHelper : NSObject {
@private
GTM_WEAK id observer_;
SEL selector_;
id userInfo_;
GTM_WEAK id target_;
NSString* keyPath_;
}
- (id)initWithObserver:(id)observer
object:(id)target
keyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options;
- (void)deregister;
@end
@interface GTMKeyValueChangeNotification ()
- (id)initWithKeyPath:(NSString *)keyPath ofObject:(id)object
userInfo:(id)userInfo change:(NSDictionary *)change;
@end
@implementation GTMKeyValueObservingHelper
// For info how and why we use these statics:
// http://lists.apple.com/archives/cocoa-dev/2006/Jul/msg01038.html
static char GTMKeyValueObservingHelperContextData;
static char* GTMKeyValueObservingHelperContext
= >MKeyValueObservingHelperContextData;
- (id)initWithObserver:(id)observer
object:(id)target
keyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options {
if((self = [super init])) {
observer_ = observer;
selector_ = selector;
userInfo_ = [userInfo retain];
target_ = target;
keyPath_ = [keyPath retain];
[target addObserver:self
forKeyPath:keyPath
options:options
context:GTMKeyValueObservingHelperContext];
}
return self;
}
- (NSString *)description {
return [NSString stringWithFormat:
@"%@ <observer = %@ keypath = %@ target = %@ selector = %@>",
[self class], observer_, keyPath_, target_,
NSStringFromSelector(selector_)];
}
- (void)dealloc {
if (target_) {
_GTMDevLog(@"Didn't deregister %@", self);
[self deregister];
}
[userInfo_ release];
[keyPath_ release];
[super dealloc];
}
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object
change:(NSDictionary *)change
context:(void *)context {
if(context == GTMKeyValueObservingHelperContext) {
GTMKeyValueChangeNotification *notification
= [[GTMKeyValueChangeNotification alloc] initWithKeyPath:keyPath
ofObject:object
userInfo:userInfo_
change:change];
[observer_ performSelector:selector_ withObject:notification];
[notification release];
} else {
// COV_NF_START
// There's no way this should ever be called.
// If it is, the call will go up to NSObject which will assert.
[super observeValueForKeyPath:keyPath
ofObject:object
change:change
context:context];
// COV_NF_END
}
}
- (void)deregister {
[target_ removeObserver:self forKeyPath:keyPath_];
target_ = nil;
}
@end
@implementation GTMKeyValueObservingCenter
+ (id)defaultCenter {
static GTMKeyValueObservingCenter *center = nil;
if(!center) {
// do a bit of clever atomic setting to make this thread safe
// if two threads try to set simultaneously, one will fail
// and the other will set things up so that the failing thread
// gets the shared center
GTMKeyValueObservingCenter *newCenter = [[self alloc] init];
if(!objc_atomicCompareAndSwapGlobalBarrier(nil,
newCenter,
(void *)¢er)) {
[newCenter release]; // COV_NF_LINE no guarantee we'll hit this line
}
}
return center;
}
- (id)init {
if((self = [super init])) {
observerHelpers_ = [[NSMutableDictionary alloc] init];
}
return self;
}
// COV_NF_START
// Singletons don't get deallocated
- (void)dealloc {
[observerHelpers_ release];
[super dealloc];
}
// COV_NF_END
- (id)dictionaryKeyForObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector {
NSString *key = nil;
if (!target && !keyPath && !selector) {
key = [NSString stringWithFormat:@"%p:", observer];
} else {
key = [NSString stringWithFormat:@"%p:%@:%p:%p",
observer, keyPath, selector, target];
}
return key;
}
- (void)addObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options {
GTMKeyValueObservingHelper *helper
= [[GTMKeyValueObservingHelper alloc] initWithObserver:observer
object:target
keyPath:keyPath
selector:selector
userInfo:userInfo
options:options];
id key = [self dictionaryKeyForObserver:observer
ofObject:target
forKeyPath:keyPath
selector:selector];
@synchronized(self) {
GTMKeyValueObservingHelper *oldHelper = [observerHelpers_ objectForKey:key];
if (oldHelper) {
_GTMDevLog(@"%@ already observing %@ forKeyPath %@",
observer, target, keyPath);
[oldHelper deregister];
}
[observerHelpers_ setObject:helper forKey:key];
}
[helper release];
}
- (void)removeObserver:(id)observer
ofObject:(id)target
forKeyPath:(NSString *)keyPath
selector:(SEL)selector {
id key = [self dictionaryKeyForObserver:observer
ofObject:target
forKeyPath:keyPath
selector:selector];
NSMutableArray *allValidHelperKeys = [NSMutableArray array];
NSArray *allValidHelpers = nil;
@synchronized(self) {
NSString *helperKey;
GTM_FOREACH_OBJECT(helperKey, [observerHelpers_ allKeys]) {
if ([helperKey hasPrefix:key]) {
[allValidHelperKeys addObject:helperKey];
}
}
#if DEBUG
if ([allValidHelperKeys count] == 0) {
_GTMDevLog(@"%@ was not observing %@ with keypath %@",
observer, target, keyPath);
}
#endif // DEBUG
allValidHelpers = [observerHelpers_ objectsForKeys:allValidHelperKeys
notFoundMarker:[NSNull null]];
[observerHelpers_ removeObjectsForKeys:allValidHelperKeys];
}
[allValidHelpers makeObjectsPerformSelector:@selector(deregister)];
}
@end
@implementation NSObject (GTMKeyValueObservingAdditions)
- (void)gtm_addObserver:(id)observer
forKeyPath:(NSString *)keyPath
selector:(SEL)selector
userInfo:(id)userInfo
options:(NSKeyValueObservingOptions)options {
_GTMDevAssert(observer && [keyPath length] && selector,
@"Missing observer, keyPath, or selector");
GTMKeyValueObservingCenter *center
= [GTMKeyValueObservingCenter defaultCenter];
GTMAssertSelectorNilOrImplementedWithArguments(
observer,
selector,
@encode(GTMKeyValueChangeNotification *),
NULL);
[center addObserver:observer
ofObject:self
forKeyPath:keyPath
selector:selector
userInfo:userInfo
options:options];
}
- (void)gtm_removeObserver:(id)observer
forKeyPath:(NSString *)keyPath
selector:(SEL)selector {
_GTMDevAssert(observer && [keyPath length] && selector,
@"Missing observer, keyPath, or selector");
GTMKeyValueObservingCenter *center
= [GTMKeyValueObservingCenter defaultCenter];
GTMAssertSelectorNilOrImplementedWithArguments(
observer,
selector,
@encode(GTMKeyValueChangeNotification *),
NULL);
[center removeObserver:observer
ofObject:self
forKeyPath:keyPath
selector:selector];
}
- (void)gtm_stopObservingAllKeyPaths {
GTMKeyValueObservingCenter *center
= [GTMKeyValueObservingCenter defaultCenter];
[center removeObserver:self
ofObject:nil
forKeyPath:nil
selector:Nil];
}
@end
@implementation GTMKeyValueChangeNotification
- (id)initWithKeyPath:(NSString *)keyPath ofObject:(id)object
userInfo:(id)userInfo change:(NSDictionary *)change {
if ((self = [super init])) {
keyPath_ = [keyPath copy];
object_ = [object retain];
userInfo_ = [userInfo retain];
change_ = [change retain];
}
return self;
}
- (void)dealloc {
[keyPath_ release];
[object_ release];
[userInfo_ release];
[change_ release];
[super dealloc];
}
- (id)copyWithZone:(NSZone *)zone {
return [[[self class] allocWithZone:zone] initWithKeyPath:keyPath_
ofObject:object_
userInfo:userInfo_
change:change_];
}
- (BOOL)isEqual:(id)object {
return ([keyPath_ isEqualToString:[object keyPath]]
&& [object_ isEqual:[object object]]
&& [userInfo_ isEqual:[object userInfo]]
&& [change_ isEqual:[object change]]);
}
- (NSString *)description {
return [NSString stringWithFormat:
@"%@ <object = %@ keypath = %@ userInfo = %@ change = %@>",
[self class], object_, keyPath_, userInfo_, change_];
}
- (NSUInteger)hash {
return [keyPath_ hash] + [object_ hash] + [userInfo_ hash] + [change_ hash];
}
- (NSString *)keyPath {
return keyPath_;
}
- (id)object {
return object_;
}
- (id)userInfo {
return userInfo_;
}
- (NSDictionary *)change {
return change_;
}
@end
#ifdef DEBUG
static void SwizzleMethodsInClass(Class cls, SEL sel1, SEL sel2) {
Method m1 = class_getInstanceMethod(cls, sel1);
Method m2 = class_getInstanceMethod(cls, sel2);
method_exchangeImplementations(m1, m2);
}
// This category exists to attempt to help deal with tricky KVO issues.
// KVO is a wonderful technology in some ways, but is extremely fragile and
// allows developers a lot of freedom to shoot themselves in the foot.
// Refactoring an app that uses a lot of KVO can be really difficult, as can
// debugging it.
// These are some tools that we have found useful when working with KVO. Note
// that these tools are only on in Debug builds.
// To enable our KVO debugging, set the GTMDebugKVO environment
// variable to 1 and you will get a whole pile of KVO logging that may help you
// track down problems.
// bash - export GTMDebugKVO=1
// csh/tcsh - setenv GTMDebugKVO 1
//
@interface NSObject (GTMDebugKeyValueObserving)
- (void)_gtmDebugAddObserver:(NSObject *)observer
forKeyPath:(NSString *)keyPath
options:(NSKeyValueObservingOptions)options
context:(void *)context;
- (void)_gtmDebugArrayAddObserver:(NSObject *)observer
toObjectsAtIndexes:(NSIndexSet *)indexes
forKeyPath:(NSString *)keyPath
options:(NSKeyValueObservingOptions)options
context:(void *)context;
- (void)_gtmDebugRemoveObserver:(NSObject *)observer
forKeyPath:(NSString *)keyPath;
- (void)_gtmDebugArrayRemoveObserver:(NSObject *)observer
fromObjectsAtIndexes:(NSIndexSet *)indexes
forKeyPath:(NSString *)keyPath;
- (void)_gtmDebugWillChangeValueForKey:(NSString*)key;
- (void)_gtmDebugDidChangeValueForKey:(NSString*)key;
@end
@implementation NSObject (GTMDebugKeyValueObserving)
GTM_METHOD_CHECK(NSObject, _gtmDebugAddObserver:forKeyPath:options:context:);
GTM_METHOD_CHECK(NSObject, _gtmDebugRemoveObserver:forKeyPath:);
GTM_METHOD_CHECK(NSObject, _gtmDebugWillChangeValueForKey:);
GTM_METHOD_CHECK(NSObject, _gtmDebugDidChangeValueForKey:);
GTM_METHOD_CHECK(NSArray,
_gtmDebugArrayAddObserver:toObjectsAtIndexes:forKeyPath:options:context:);
GTM_METHOD_CHECK(NSArray,
_gtmDebugArrayRemoveObserver:fromObjectsAtIndexes:forKeyPath:);
+ (void)load {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
NSDictionary *env = [[NSProcessInfo processInfo] environment];
id debugKeyValue = [env valueForKey:@"GTMDebugKVO"];
BOOL debug = NO;
if ([debugKeyValue isKindOfClass:[NSNumber class]]) {
debug = [debugKeyValue intValue] != 0 ? YES : NO;
} else if ([debugKeyValue isKindOfClass:[NSString class]]) {
debug = ([debugKeyValue hasPrefix:@"Y"] || [debugKeyValue hasPrefix:@"T"] ||
[debugKeyValue intValue]);
}
Class cls = Nil;
if (debug) {
cls = [NSObject class];
SwizzleMethodsInClass(cls,
@selector(addObserver:forKeyPath:options:context:),
@selector(_gtmDebugAddObserver:forKeyPath:options:context:));
SwizzleMethodsInClass(cls,
@selector(removeObserver:forKeyPath:),
@selector(_gtmDebugRemoveObserver:forKeyPath:));
SwizzleMethodsInClass(cls,
@selector(willChangeValueForKey:),
@selector(_gtmDebugWillChangeValueForKey:));
SwizzleMethodsInClass(cls,
@selector(didChangeValueForKey:),
@selector(_gtmDebugDidChangeValueForKey:));
cls = [NSArray class];
SwizzleMethodsInClass(cls,
@selector(addObserver:toObjectsAtIndexes:forKeyPath:options:context:),
@selector(_gtmDebugArrayAddObserver:toObjectsAtIndexes:forKeyPath:options:context:));
SwizzleMethodsInClass(cls,
@selector(removeObserver:fromObjectsAtIndexes:forKeyPath:),
@selector(_gtmDebugArrayRemoveObserver:fromObjectsAtIndexes:forKeyPath:));
}
[pool drain];
}
- (void)_gtmDebugAddObserver:(NSObject *)observer
forKeyPath:(NSString *)keyPath
options:(NSKeyValueObservingOptions)options
context:(void *)context {
_GTMDevLog(@"Adding observer %@ to %@ keypath '%@'", observer, self, keyPath);
[self _gtmDebugAddObserver:observer forKeyPath:keyPath
options:options context:context];
}
- (void)_gtmDebugArrayAddObserver:(NSObject *)observer
toObjectsAtIndexes:(NSIndexSet *)indexes
forKeyPath:(NSString *)keyPath
options:(NSKeyValueObservingOptions)options
context:(void *)context {
_GTMDevLog(@"Array adding observer %@ to indexes %@ of %@ keypath '%@'",
observer, indexes, self, keyPath);
[self _gtmDebugArrayAddObserver:observer
toObjectsAtIndexes:indexes
forKeyPath:keyPath
options:options context:context];
}
- (void)_gtmDebugRemoveObserver:(NSObject *)observer
forKeyPath:(NSString *)keyPath {
_GTMDevLog(@"Removing observer %@ from %@ keypath '%@'",
observer, self, keyPath);
[self _gtmDebugRemoveObserver:observer forKeyPath:keyPath];
}
- (void)_gtmDebugArrayRemoveObserver:(NSObject *)observer
fromObjectsAtIndexes:(NSIndexSet *)indexes
forKeyPath:(NSString *)keyPath {
_GTMDevLog(@"Array removing observer %@ from indexes %@ of %@ keypath '%@'",
indexes, observer, self, keyPath);
[self _gtmDebugArrayRemoveObserver:observer
fromObjectsAtIndexes:indexes
forKeyPath:keyPath];
}
- (void)_gtmDebugWillChangeValueForKey:(NSString*)key {
_GTMDevLog(@"Will change '%@' of %@", key, self);
[self _gtmDebugWillChangeValueForKey:key];
}
- (void)_gtmDebugDidChangeValueForKey:(NSString*)key {
_GTMDevLog(@"Did change '%@' of %@", key, self);
[self _gtmDebugDidChangeValueForKey:key];
}
@end
#endif // DEBUG
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