过滤树控制器 [英] Filtering A Tree Controller

问题描述

我现在已经弄清楚如何过滤一个NSTreeController，为此我有子类NSManagedObject并添加了一些代码到我的应用程序委托，我也绑定我的NSSearchField到我的应用程序代理的filterPredicate，但我认为需要连接我的NSTreeController和NSSearchField在某种程度上，使其工作。
下面我已经发布了所有的代码，我已经使用到目前为止尝试，并使其工作。

---

strong> NSManagedObject子类头文件。

  @interface Managed_Object_Sub_Class：NSManagedObject {
 NSArray * filteredChildren ; //这应该修复编译器错误
} 
 
  - （NSArray *）filteredChildren; 
 
 
 @end 
  

NSManagedObject子类实现文件。

  @implementation Managed_Object_Sub_Class 
 
 static char * FilteredChildrenObservationContext; 
 
  - （id）initWithEntity：（NSEntityDescription *）entity insertIntoManagedObjectContext：（NSManagedObjectContext *）context {
 if（self = [super initWithEntity：entity insertIntoManagedObjectContext：context]）{
 [[NSApp delegate] addObserver：self forKeyPath：@filterPredicateoptions：0 context：& FilteredChildrenObservationContext]; 
 [self addObserver：self forKeyPath：@subGroupoptions：0 context：& FilteredChildrenObservationContext]; 
} 
 return self; 
} 
 
 //使用finalize和GC 
  - （void）dealloc {
 [[NSApp delegate] removeObserver：self forKeyPath：@filterPredicate]; 
 [self removeObserver：self forKeyPath：@subGroup]; 
 [super dealloc] 
} 
 
  - （NSArray *）filteredChildren {
 if（filteredChildren == nil）{
 NSPredicate * predicate = [[NSApp delegate] filterPredicate]; 
 if（predicate）
 filteredChildren = [[self valueForKey：@subGroup] filteredArrayUsingPredicate：predicate] copy]; 
 else 
 filteredChildren = [[self valueForKey：@subGroup] copy]; 
} 
 return filteredChildren; 
} 
 
  - （void）observeValueForKeyPath：（NSString *）keyPath ofObject：（id）object change：（NSDictionary *）change context：（void *）context {
 if （context ==& FilteredChildrenObservationContext）{
 [self willChangeValueForKey：@filteredChildren]; 
 [filteredChildren release]; 
 filteredChildren = nil; 
 [self didChangeValueForKey：@filteredChildren]; 
} else {
 [super observeValueForKeyPath：keyPath ofObject：object change：change context：context]; 
} 
} 
 
 @end 
  

strong>添加到应用程序代理头文件的代码

  NSPredicate * filterPredicate; 
  

添加到应用代理实施文件的代码

   - （NSPredicate *）filterPredicate {
 return filterPredicate; 
} 
 
  - （void）setFilterPredicate：（NSPredicate *）newFilterPredicate {
 if（filterPredicate！= newFilterPredicate）{
 [filterPredicate release]; 
 filterPredicate = [newFilterPredicate retain]; 
} 
} 
  

搜索字段绑定 / p>

---

这还没有工作，所以这就是为什么我问我从这里需要做什么，使其工作，像我说我认为我需要连接NSSearchField和NSTreeController以某种方式在一起。

解决方案

再次我hav回答了我自己的问题，我也希望这将帮助其他因此他们知道如何过滤一个NSTreeController。

要使它的工作从我的帖子上面做以下。

1.对于您的实体，将类设置为我的Case JGManagedObject中的NSManagedObject子类。

I have now nearly figured out how to Filter a NSTreeController, to do this I have sub-classed NSManagedObject and added some code to my App Delegate, I have also bound my NSSearchField to the filterPredicate of my App Delegate but I think I need to connect my NSTreeController and NSSearchField in some way to make it work. Below I have posted all the code I have used so far to try and make it work.

---

NSManagedObject Sub-Class Header File.

@interface Managed_Object_Sub_Class : NSManagedObject {
    NSArray *filteredChildren; // this should fix the compiler error
}

- (NSArray *)filteredChildren;


@end

NSManagedObject Sub-Class Implementation File.

@implementation Managed_Object_Sub_Class

static char *FilteredChildrenObservationContext;

- (id)initWithEntity:(NSEntityDescription *)entity insertIntoManagedObjectContext:(NSManagedObjectContext *)context {
    if (self = [super initWithEntity:entity insertIntoManagedObjectContext:context]) {
        [[NSApp delegate] addObserver:self forKeyPath:@"filterPredicate" options:0 context:&FilteredChildrenObservationContext];
        [self addObserver:self forKeyPath:@"subGroup" options:0 context:&FilteredChildrenObservationContext];
    }
    return self;
}

// use finalize with GC
- (void)dealloc {
    [[NSApp delegate] removeObserver:self forKeyPath:@"filterPredicate"];
    [self removeObserver:self forKeyPath:@"subGroup"];
    [super dealloc];
}

- (NSArray *)filteredChildren {
    if (filteredChildren == nil) {
        NSPredicate *predicate = [[NSApp delegate] filterPredicate];
        if (predicate)
            filteredChildren = [[[self valueForKey:@"subGroup"] filteredArrayUsingPredicate:predicate] copy];
        else
            filteredChildren = [[self valueForKey:@"subGroup"] copy];
    }
    return filteredChildren;
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
    if (context == &FilteredChildrenObservationContext) {
        [self willChangeValueForKey:@"filteredChildren"];
        [filteredChildren release];
        filteredChildren = nil;
        [self didChangeValueForKey:@"filteredChildren"];
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

@end

Code Added To App Delegate Header File

NSPredicate *filterPredicate;

Code Added To App Delegate Implementation File

- (NSPredicate *)filterPredicate {
    return filterPredicate;
}

- (void)setFilterPredicate:(NSPredicate *)newFilterPredicate {
    if (filterPredicate != newFilterPredicate) {
        [filterPredicate release];
        filterPredicate = [newFilterPredicate retain];
    }
}

Search Field Binding

---

This doesn't work yet, and so that is why I am asking what I need to do from here to make it work, like I said I think I need to connect the NSSearchField and NSTreeController Together in some way.

解决方案

Again I hav answered my own question, I also hope that this will help other people so they know how to Filter a NSTreeController.

To make it work from my post above do the following.

1.For your entity set the Class as your NSManagedObject Sub-Class in my Case JGManagedObject.

2.For your search field in IB set the predicate format to what you want to Filter ( The Property in your entity, for me it is name).

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