我怎样才能从志愿方法observeValueForKeyPath变化字典INT值：ofObject变

我观察的变化rate ，通过调用像这样在它下面的方法的AVPlayer的性质：

addObserver:sharedPlayerManagerInstance
 forKeyPath:@"rate"
    options:NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld
    context:0]; 

该change的字典，我回去从observeValueForKeyPath:ofObject:change:context:因此：

change = { kind: 1,
            new: 1,
            old: 0 }

我检查了每类值，它原来是__NSCFNumber。 然而，当我尝试转换[change objectForKey:@"new"]或[change objectForKey:@"old"]为一个int，NSInteger的，的NSNumber，甚至试过的NSString等，它适用于“老”，但它给我的“新”分析错误：

error: expected a type
error: 1 errors parsing expression

我真的需要对它们进行比较，我也搞不清楚。 难道这是iOS中的错误吗？

Answer 1:

目标C

-(void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
NSNumber * newValue = [change objectForKey:NSKeyValueChangeNewKey];
NSInteger integerValue = newValue.integerValue;
int intValue = newValue.intValue;
}

迅速

   override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {
        if let newValue = change[NSKeyValueChangeNewKey] as? NSNumber{
            let intvalue = newValue.intValue //To int
        }
    }

Answer 2:

斯威夫特3：

if let newValue = change?[NSKeyValueChangeKey.newKey] as? NSNumber {
     // Do stuff
}

文章来源: How can I get int values from the change dictionary in KVO method observeValueForKeyPath:ofObject:change:context:?