手動觸發(fā) kvo

過程如下：

重寫automaticallyNotifiesObserversForKey 返回 NO
非可變?nèi)萜鲗傩?在 set 中添加方法 willChangeValueForKey,didChangeValueForKey
可變?nèi)萜鲗傩愿鶕?jù) kvc 創(chuàng)建代理對象拗窃，并在里面調(diào)用方法 willChange:valuesAtIndexes:forKey:, didChange:valuesAtIndexes:forKey:
kvo 響應(yīng)方法 observeValueForKeyPath:ofObject:change:context:.

具體過程

重新方法 automaticallyNotifiesObserversForKey , 對需要手動控制 kvo 的 key 返回 NO
我們把屬性 name, number, arr, mutableArr 都設(shè)為手動觸發(fā) kvo

    + (BOOL)automaticallyNotifiesObserversForKey:(NSString *)key{
        BOOL automatic = NO;
        if ([key isEqualToString:@"name"]) {
            automatic = NO;
        }else if ([key isEqualToString:@"number"]){
            automatic = NO;
        }else if ([key isEqualToString:@"arr"]){
            automatic = NO;
        }else if ([key isEqualToString:@"mutableArr"]){
            automatic = NO;
        }else {
            automatic = [super automaticallyNotifiesObserversForKey:key];
        }
        return automatic;
    }

在屬性 set 方法中手動觸發(fā) kvo, willChangeValueForKey, didChangeValueForKey

    // 手動改管理 kvo 觸發(fā)可训，有個明顯的好處，就是，我們在不需要觸發(fā)kvo時可以很容易的停止觸發(fā)，如下
    // 當 name 在設(shè)值 前和 設(shè)值后 是一樣的比如都是 王小小，我們就可以不觸發(fā)kvo
    // 如果是 自動 kvo 就無法達到這樣的控制效果。
    - (void)setName:(NSString *)name{
    if (![_name isEqualToString:name]) {
        [self willChangeValueForKey:@"name"];
        _name = name;
        [self didChangeValueForKey:@"name"];
        }
    }
    // 設(shè)值 kvo 觸發(fā)條件特石， 只有當 bunber > 10 的時候，才會觸發(fā) kvo鳖链。
    - (void)setNumber:(int)number{
        if (number>10) {
            [self willChangeValueForKey:@"number"];
            _number = number;
            [self didChangeValueForKey:@"number"];
        }
    }

    - (void)setArr:(NSArray<NSString *> *)arr{
        [self willChangeValueForKey:@"arr"];
        _arr = arr;
        [self didChangeValueForKey:@"arr"];
    }

在可變?nèi)萜髦杏|發(fā) kvo姆蘸，結(jié)合 kvc 可變?nèi)萜鞔韺ο髣?chuàng)建。
需要實現(xiàn)一對刪除和插入的方法, 并在這些方法中調(diào)用方法 willChange:valuesAtIndexes:forKey:, didChange:valuesAtIndexes:forKey:

        // 可變?nèi)萜魈砑邮謩觡vo芙委，可變?nèi)萜鲀?nèi)部元素發(fā)生添加逞敷，移除，替換時觸發(fā)kvo
        // 插入單個 元素
        - (void)insertObject:(NSString *)object inMutableArrAtIndex:(NSUInteger)index{
            [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:[NSIndexSet indexSetWithIndex:index] forKey:@"mutableArr"];
            [_mutableArr insertObject:object atIndex:index];
             [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:[NSIndexSet indexSetWithIndex:index] forKey:@"mutableArr"];
        }

        // 刪除 單個元素
        - (void)removeObjectFromMutableArrAtIndex:(NSUInteger)index{
            [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:[NSIndexSet indexSetWithIndex:index] forKey:@"mutableArr"];
            [_mutableArr removeObjectAtIndex:index];
            [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:[NSIndexSet indexSetWithIndex:index] forKey:@"mutableArr"];
        }
        // 插入 多個元素
        - (void)insertMutableArr:(NSArray *)array atIndexes:(NSIndexSet *)indexes{
            [self willChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:@"mutableArr"];
            [_mutableArr insertObjects:array atIndexes:indexes];
            [self didChange:NSKeyValueChangeInsertion valuesAtIndexes:indexes forKey:@"mutableArr"];
        }
        // 刪除多個元素
        - (void)removeMutableArrAtIndexes:(NSIndexSet *)indexes{
            [self willChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:@"mutableArr"];
            [_mutableArr removeObjectsAtIndexes:indexes];
            [self didChange:NSKeyValueChangeRemoval valuesAtIndexes:indexes forKey:@"mutableArr"];
        }
        // 替換 單個
        - (void)replaceObjectInMutableArrAtIndex:(NSUInteger)index withObject:(id)object{
            [self willChange:NSKeyValueChangeReplacement valuesAtIndexes:[NSIndexSet indexSetWithIndex:index] forKey:@"mutableArr"];
            [_mutableArr replaceObjectAtIndex:index withObject:object];
            [self didChange:NSKeyValueChangeReplacement valuesAtIndexes:[NSIndexSet indexSetWithIndex:index] forKey:@"mutableArr"];
        }
        // 替換 多個
        - (void)replaceMutableArrAtIndexes:(NSIndexSet *)indexes withMutableArr:(NSArray *)array{
            [self willChange:NSKeyValueChangeReplacement valuesAtIndexes:indexes forKey:@"mutableArr"];
            [_mutableArr replaceObjectsAtIndexes:indexes withObjects:array];
            [self didChange:NSKeyValueChangeReplacement valuesAtIndexes:indexes forKey:@"mutableArr"];
        }

外部調(diào)用

    // 必須通過 kvc 拿到 屬性
    NSMutableArray *mutableArr = [obj mutableArrayValueForKey:@"mutableArr"];
    // 添加一個元素
    [mutableArr addObject:@"100"];
    // 刪除一個元素
    [mutableArr removeObjectAtIndex:0];
    // 添加多個元素
    [mutableArr addObjectsFromArray:@[@"90",@"91"]];
    // 刪除多個元素
    [mutableArr removeObjectsAtIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, 2)]];
    // 替換一個元素
    [mutableArr replaceObjectAtIndex:0 withObject:@"替換"];
    // 替換多個元素
    NSArray *objs = @[@"替換: 1",@"替換: 2"];
    [mutableArr replaceObjectsAtIndexes:[NSIndexSet indexSetWithIndexesInRange:NSMakeRange(0, objs.count)] withObjects:objs];

observeValueForKeyPath 響應(yīng)
- change 參數(shù)：這是一個字典里面包含的key 有
  kind: NSKeyValueChange灌侣，跟 willChangeValueForKey 中的保持一致
  indexes: String, 元素變更的位置或者 range
  new: 設(shè)值的新值
  old: 之前的舊值

代碼地址

手動 觸發(fā) kvo

手動 觸發(fā) kvo

手動觸發(fā) kvo

手動觸發(fā) kvo