一步一步熟悉Mac-app开发（六）之NSOutlineView

#概要
阶段一，完成数据的显示。
阶段二，完成数据拖拽的调整。(存在未知问题)
阶段三，实现撤销功能。(存在问题)

#阶段一实现数据的显示
1.新建项目，打开storyboard，将source list拖拽直默认的view controller中。

2.将tree controller和object拖拽至默认的view controller的顶部。(不会的请看前文)

3.点击选中object，设置其【Custom Class】为“NSMutableArray”，设置其【Document Label】为playlits。

4.点击选中Tree Controller，按住Control键将其拖拽至object图标上，选择content。

5.点击选中Tree Controller，设置其Children为children、Ledf为isLeaf、Class Name为Playlist。(聪明的你知道我们下一步要做什么了吗？)

6.新建一个NSObject的子类Playlist，声明两个属性name和creator，声明并实现isLeaf和初始化方法。

//Playlist.h
#import <Cocoa/Cocoa.h>
@interface Playlist : NSObject
@property NSString *name;
@property NSString *creator;
- (bool) isLeaf;
- (id) init;
- (id) initWithCustom:(NSString*)name;
@end

#import "Playlist.h"

@implementation Playlist
-(id) init{
    self = [super init];
    if(self){
        _name = @"New Player";
        _creator = @"N/A";
    }
    return self;
}

-(id) initWithCustom:(NSString*)name{
    self = [super init];
    if(self){
        _name = name;
        _creator = @"N/A";
    }
    return self;
}

-(bool) isLeaf{
    return YES;
}
@end

7、绑定。
7-1、将Table Column与Tree Controller进行绑定；

7-2将HEADER CELL与Table Cell View进行绑定，并设置其key path为objectvalue.name；

7-3、将Table View Cell与Table Cell View进行绑定，设置为其key path为objectvalue.name。

7-4、最后将View Controller做为Outline View的Datasource与Delegate。

8.拖拽大法，将outline view与tree controller拖拽直ViewController.h中。

并且在ViewController.h中添加NSOutlineViewDataSource和NSOutlineViewDelegate协议。

//ViewController.h
#import <Cocoa/Cocoa.h>
@interface ViewController : NSViewController<NSOutlineViewDataSource,NSOutlineViewDelegate>
@property (weak) IBOutlet NSOutlineView *outlineView;
@property (strong) IBOutlet NSTreeController *treeController;
@end

9.在ViewController.m中添加addData方法，并在viewDidLoad中调用，实现outlineView的协议方法。

#import "ViewController.h"
#import "Playlist.h"
@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    // Do any additional setup after loading the view.
    [self addData];
}

//内部方法1:初始化数据
- (void) addData{
    NSDictionary *root = @{@"name":@"Library",@"isLeaf":@NO};
    
    NSMutableArray *array =[[NSMutableArray alloc] initWithCapacity:(NSUInteger)10];
    [array addObject:[[Playlist alloc] initWithCustom:@"New Player1"]];
    [array addObject:[[Playlist alloc] initWithCustom:@"New Player2"]];
    
    NSMutableDictionary *dict = [[NSMutableDictionary alloc] initWithDictionary:root];
    
    [dict setObject:array forKey:@"children"];
    
    [_treeController addObject:dict];
}

//内部方法2:判断是否为头
- (bool) isHeader:(id)Item{
    Item = (NSTreeNode*)Item;
    if(Item){
        return ![[Item representedObject] isKindOfClass:[Playlist class]];
    }
    return ![Item isKindOfClass:[Playlist class]];
}

//实现协议方法
- (NSView *)outlineView:(NSOutlineView *)outlineView viewForTableColumn:(NSTableColumn *)tableColumn item:(id)item{
    if([self isHeader:item]){
        return [outlineView makeViewWithIdentifier:@"HeaderCell" owner:self];
    }
    return [outlineView makeViewWithIdentifier:@"DataCell" owner:self];
}

- (void)setRepresentedObject:(id)representedObject {
    [super setRepresentedObject:representedObject];

    // Update the view, if already loaded.
}
@end

10.阶段一完成，效果如下。

#阶段二实现拖拽调整数据功能

1.打开ViewController.m中，在viewDidLoad方法中新增代码。

//阶段二
[_outlineView expandItem:nil expandChildren:YES];   //自动展开
//拖拽事件相关
NSMutableArray *arr = [[NSMutableArray alloc] init];
[arr addObject:NSPasteboardTypeString];
[_outlineView registerForDraggedTypes:arr];

2.添加以下三个函数。

//阶段二之支持拖拽
- (id<NSPasteboardWriting>)outlineView:(NSOutlineView *)outlineView pasteboardWriterForItem:(id)item{
    Playlist *playlist = [item representedObject];
    if ([playlist isKindOfClass:[Playlist class]]){
        NSPasteboardItem* pbItem = [[NSPasteboardItem alloc] init];
        [pbItem setString:playlist.name forType:NSPasteboardTypeString];
        return pbItem;
    }
    return nil;
}

//阶段二之判断是否为有效拖拽
- (NSDragOperation)outlineView:(NSOutlineView *)outlineView validateDrop:(id<NSDraggingInfo>)info proposedItem:(id)item proposedChildIndex:(NSInteger)index{
    bool canDrag = index>=0 && item!=nil;
    if (!canDrag){
        return NSDragOperationNone;
    }
    return NSDragOperationMove;
}

//阶段二之拖拽调整位置
- (BOOL)outlineView:(NSOutlineView *)outlineView acceptDrop:(id<NSDraggingInfo>)info item:(id)item childIndex:(NSInteger)index{
    
    NSPasteboard* pb = [info draggingPasteboard];
    NSString *name = [pb stringForType:NSPasteboardTypeString];
    NSTreeNode *sourceNode = nil;
    
    if([(NSTreeNode*)item childNodes] != nil){
        for(id node in [item childNodes]){
            Playlist * playlist = [node representedObject];
            if([playlist isKindOfClass:[Playlist class]]){
                if([playlist.name isEqualToString:name]){
                    sourceNode = node;
                }
            }
        }
    }
    if(sourceNode == nil){
        return NO;
    }
    
    NSUInteger indexs[] ={0,index};
    NSIndexPath* toIndexPath = [[NSIndexPath alloc] initWithIndexes:indexs length:2];
    [_treeController moveNode:sourceNode toIndexPath:toIndexPath];
    
    return YES;
}

3.阶段二，完成！

#阶段三实现撤销功能

1.实现两个协议方法。

//阶段三之是否为GroupItem
- (BOOL)outlineView:(NSOutlineView *)outlineView isGroupItem:(id)item{
    return [self isHeader:item];
}

//阶段三之执行撤销动作
- (void)reverse:(NSTreeNode*)sourceNode fromIndexPath:(NSIndexPath*)fromIndexPath{
    [_treeController moveNode:sourceNode toIndexPath:fromIndexPath];
}

2.添加部分代码至outlineView(acceptDrop)函数中。

//阶段二之拖拽调整位置
- (BOOL)outlineView:(NSOutlineView *)outlineView acceptDrop:(id<NSDraggingInfo>)info item:(id)item childIndex:(NSInteger)index{
    
    NSPasteboard* pb = [info draggingPasteboard];
    NSString *name = [pb stringForType:NSPasteboardTypeString];
    NSTreeNode *sourceNode = nil;
    
    if([(NSTreeNode*)item childNodes] != nil){
        for(id node in [item childNodes]){
            Playlist * playlist = [node representedObject];
            if([playlist isKindOfClass:[Playlist class]]){
                if([playlist.name isEqualToString:name]){
                    sourceNode = node;
                }
            }
        }
    }
    if(sourceNode == nil){
        return NO;
    }
    
    //阶段三之记录原始路径
    NSIndexPath* fromIndexPath = [_treeController selectionIndexPath];
    
    NSUInteger indexs[] ={0,index};
    NSIndexPath* toIndexPath = [[NSIndexPath alloc] initWithIndexes:indexs length:2];
    [_treeController moveNode:sourceNode toIndexPath:toIndexPath];
    
    //阶段三之配置undoManager，执行reverse动作。
    [[self.undoManager prepareWithInvocationTarget:self] reverse:sourceNode fromIndexPath:fromIndexPath];
    [self.undoManager setActionName:@"Move"];
    
    return YES;
}

3.阶段三完成，效果如下。

#思考
这里有个小问题，在拖拽p2时，必须先点击选中p2，再去将p2拖拽至p1，否则在撤销时，就会存在p2与Library位置互换的BUG。
这个可爱的BUG就交给你们去修复啦！