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obj-c编程15[Cocoa实例03]:MVC以及归档化示例

    前面的博文里介绍了归档和解档,这里我们把它实际应用到一个简单的代码中去,将它作为一个多文档应用程序的打开和保存的背后支持。另外这里介绍一下MVC思想,这个在任何语言里都会有,它是一种设计思想,主要可以概括为一个程序由3部分组成:

1 模式:是程序的数据支持;

2 视图:是程序的表示支持;

3 控制:连接模式和视图,将程序构为一个整体;

    Cocoa框架中对MVC提供了非常好的支持,你只需要写很少的代码就可以完成一个程序的MVC绑定了。下面的例子中,我生成一个基于多文档的程序,使用了NSArrayController类作为控制器,它的数据源为NSArray,其中每个元素由我定义的类Person来描述;主窗口中的tab_view作为主类中的outlets,主类为Document,它派生自NSDocument用来支持多文档中的每一个文档窗口。


添加add和remove按钮,都与NSArrayController中的add和remove方法绑定;tab_view控件的两列分别与Person类中的2个属性绑定,每一行自然是Person数组中的每一个Person对象了。这样每个视图中的数据表示(tab_view)通过控制器与模式相连,视图内容的改变(通过add和remove按钮)也通过控制器从而导致模式数据的改变;而模式自身的改变(通过读档操作)也会更新视图的显示哦。这样保证了视图和模式的独立性:模式可以在其他视图上显示,而视图也可以绑定其他的模式。

    最后,利用归档化实现了程序的save和open功能,也基本没写几行代码,而且save后的文件也自动与我们的程序绑定起来,如果双击该文件,会自动用我们的app打开哦,真是十分的方便。具体请看代码:

//
//  Document.h
//  mac_doc
//
//  Created by kinds on 14-7-7.
//  Copyright (c) 2014年 kinds. All rights reserved.
//

#import <Cocoa/Cocoa.h>

@interface Document : NSDocument{
	IBOutlet NSTableView *tab_view;
	NSMutableArray *persons;
}

-(void)setPersons:(NSMutableArray *)ary;

@end

//
//  Document.m
//  mac_doc
//
//  Created by kinds on 14-7-7.
//  Copyright (c) 2014年 kinds. All rights reserved.
//

#import "Document.h"

@interface Document ()

@end

@implementation Document
            
- (instancetype)init {
    self = [super init];
    if (self) {
		// Add your subclass-specific initialization here.
		persons = [[NSMutableArray alloc]init];
    }
    return self;
}

-(void)setPersons:(NSMutableArray *)ary{
	if(ary == persons) return;
	persons = ary;
}

- (void)windowControllerDidLoadNib:(NSWindowController *)aController {
	[super windowControllerDidLoadNib:aController];
	                            
	// Add any code here that needs to be executed once the windowController has loaded the document's window.
	                            
}

+ (BOOL)autosavesInPlace {
	return YES;
}

- (NSString *)windowNibName {
	// Override returning the nib file name of the document
	// If you need to use a subclass of NSWindowController or if your document supports multiple NSWindowControllers, you should remove this method and override -makeWindowControllers instead.
	return @"Document";
}

- (NSData *)dataOfType:(NSString *)name error:(NSError **)out_err {
	// Insert code here to write your document to data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning nil.
	// You can also choose to override -fileWrapperOfType:error:, -writeToURL:ofType:error:, or -writeToURL:ofType:forSaveOperation:originalContentsURL:error: instead.
	[[tab_view window] endEditingFor:nil];
	return [NSKeyedArchiver archivedDataWithRootObject:persons];
}

- (BOOL)readFromData:(NSData *)data ofType:(NSString *)name error:(NSError **)out_err {
	// Insert code here to read your document from the given data of the specified type. If outError != NULL, ensure that you create and set an appropriate error when returning NO.
	// You can also choose to override -readFromFileWrapper:ofType:error: or -readFromURL:ofType:error: instead.
	// If you override either of these, you should also override -isEntireFileLoaded to return NO if the contents are lazily loaded.
	NSMutableArray *new_ary = nil;
	@try{
		new_ary = [NSKeyedUnarchiver unarchiveObjectWithData:data];
	}@catch(NSException *e){
		NSLog(@"exception = %@",e);
		if(out_err){
			NSDictionary *d = [NSDictionary dictionaryWithObject:							   @"data is corrupted!" 														  forKey:NSLocalizedFailureReasonErrorKey];
			*out_err = [NSError errorWithDomain:NSOSStatusErrorDomain 										   code:unimpErr userInfo:d];
		}
		return NO;
	}
	[self setPersons:new_ary];
	return YES;
}

@end

//
//  Person.h
//  mac_doc
//
//  Created by kinds on 14-7-7.
//  Copyright (c) 2014年 kinds. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Person : NSObject <NSCoding>{
	NSString *name;
	float exp_raise;
}

@property(readwrite,copy)NSString *name;
@property(readwrite)float exp_raise;

@end

//
//  Person.m
//  mac_doc
//
//  Created by kinds on 14-7-7.
//  Copyright (c) 2014年 kinds. All rights reserved.
//

#import "Person.h"

@implementation Person

@synthesize name,exp_raise;

-(id)initWithCoder:(NSCoder *)coder{
	self = [super init];
	if(self){
		name = [coder decodeObjectForKey:@"name"];
		exp_raise = [coder decodeFloatForKey:@"exp_raise"];
	}
	return self;
}

-(void)encodeWithCoder:(NSCoder *)coder{
	[coder encodeObject:name forKey:@"name"];
	[coder encodeFloat:exp_raise forKey:@"exp_raise"];
}

-(id)init{
	self = [super init];
	if(self){
		exp_raise = 0.05;
		name = @"no_name";
	}
	return self;
}

-(void)setNilValueForKey:(NSString *)key{
	if([key isEqualToString:@"exp_raise"])
		self.exp_raise = 0.0;
	else
		[super setNilValueForKey:key];
}

@end

程序执行界面如下:


我们还可以设置私有存档文件的图标以及扩展名,如下图: