使用NSData创建自定义档案

作者:追风剑情 发布于:2019-3-8 16:23 分类:Objective-C

示例:多个不同对象存储到同一个归档文件中

#import <Foundation/Foundation.h>

@interface Foo : NSObject <NSCoding>
@property (copy, nonatomic) NSString *strVal;
@property int intVal;
@property float floatVal;

-(void) encodeWithCoder: (NSCoder *) encoder;
-(id) initWithCoder: (NSCoder *) decoder;
@end

@implementation Foo
@synthesize strVal, intVal, floatVal;
-(void) encodeWithCoder: (NSCoder *) encoder
{
    //[super encodeWithCoder: encoder];//如果有父类
    // key通常由类名+变量名组成
    [encoder encodeObject: strVal forKey: @"FoostrVal"];
    [encoder encodeInt: intVal forKey: @"FoointVal"];
    [encoder encodeFloat: floatVal forKey: @"FoofloatVal"];
}

-(id) initWithCoder: (NSCoder *) decoder
{
    strVal = [decoder decodeObjectForKey: @"FoostrVal"];
    intVal = [decoder decodeIntForKey: @"FoointVal"];
    floatVal = [decoder decodeFloatForKey: @"FoofloatVal"];
    return self;
}
@end
//-------------------------Moo类----------------------------------
@interface Moo : NSObject <NSCoding>
@property (copy, nonatomic) NSString *strVal;
@property int intVal;
@property float floatVal;

-(void) encodeWithCoder: (NSCoder *) encoder;
-(id) initWithCoder: (NSCoder *) decoder;
@end

@implementation Moo
@synthesize strVal, intVal, floatVal;
-(void) encodeWithCoder: (NSCoder *) encoder
{
    //[super encodeWithCoder: encoder];//如果有父类
    // key通常由类名+变量名组成
    [encoder encodeObject: strVal forKey: @"FoostrVal"];
    [encoder encodeInt: intVal forKey: @"FoointVal"];
    [encoder encodeFloat: floatVal forKey: @"FoofloatVal"];
}

-(id) initWithCoder: (NSCoder *) decoder
{
    strVal = [decoder decodeObjectForKey: @"FoostrVal"];
    intVal = [decoder decodeIntForKey: @"FoointVal"];
    floatVal = [decoder decodeFloatForKey: @"FoofloatVal"];
    return self;
}
@end
//------------------------- Main -----------------------
int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Foo *myFoo = [[Foo alloc] init];
        Moo *myMoo = [[Moo alloc] init];
        
        NSMutableData *dataArea;
        NSKeyedArchiver *archiver;
        
        myFoo.strVal = @"[Foo] This is the string";
        myFoo.intVal = 100;
        myFoo.floatVal = 1.1;
        
        myMoo = [[Moo alloc] init];
        myMoo.strVal = @"[Moo] this is the string";
        myMoo.intVal = 200;
        myMoo.floatVal = 2.2;
        
        // 设置数据区,并将其连接到一个NSKeyedArchiver对象
        dataArea = [NSMutableData data];
        archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData: dataArea];
        
        // 开始存档
        [archiver encodeObject: myFoo forKey: @"myfoo"];
        [archiver encodeObject: myMoo forKey: @"mymoo"];
        [archiver finishEncoding];
        
        // 将存档的数据区写到文件
        if ([dataArea writeToFile: @"myArchive" atomically: YES] == NO)
            NSLog(@"Archiving failed!");
        
        //------------- 读取归档数据 ---------------
        
        NSKeyedUnarchiver *unarchiver;
        NSData *dataArea1;
        Foo *myFoo1;
        Moo *myMoo1;
        
        // 从归档文件中读取并连接NSKeyedUnarchiver对象
        dataArea1 = [NSData dataWithContentsOfFile: @"myArchive"];
        if (!dataArea1) {
            NSLog(@"Can't read back archive file!");
            return 1;
        }
        
        unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData: dataArea1];
        
        // 解码以前存储在归档文件中的对象
        myFoo1 = [unarchiver decodeObjectForKey: @"myfoo"];
        myMoo1 = [unarchiver decodeObjectForKey: @"mymoo"];
        [unarchiver finishDecoding];
        
        // 验证是否还原成功
        NSLog(@"\n  [myFoo1] strVal=%@, intVal=%i, floatVal=%g",
              myFoo1.strVal, myFoo1.intVal, myFoo1.floatVal);
        
        NSLog(@"\n  [myMoo1] strVal=%@, intVal=%i, floatVal=%g",
              myMoo1.strVal, myMoo1.intVal, myMoo1.floatVal);
    }
    return 0;
}
运行测试
111.png


标签: Objective-C

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