OC学习笔记21--OC中集合类的读写文件操作及NSData与NSValue

#import    


// 定义一个Scores结构体
typedef struct {
	double mathScore,engScore,cScore;
} Scores;

NSString * NSStringFromScores(Scores s);

int main(int argc, const char * argv[])  
{        
    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
    NSFileManager *fm=[NSFileManager defaultManager];
     
   	NSString * aryPath= @"C:/Users/Administrator/Desktop/ary.xml";
   	NSString * dictPath= @"C:/Users/Administrator/Desktop/dict.xml";
   	
   	// *1> OC数组的读写文件操作
   	NSArray *sary= [NSArray arrayWithObjects:@"Jack",@"Tommy",@"Bolt",nil];
   	BOOL aryFlag=[sary writeToFile:aryPath atomically:YES];
   	if(aryFlag)
   	{
   		sary=[NSArray arrayWithContentsOfFile:aryPath];
   		NSLog(@"\naryFromFile=\n%@",sary);
   	}
   	
   	// *2> OC字典的读写文件操作
   	NSMutableDictionary * dict = [NSMutableDictionary dictionary];
   	[dict setValue:sary forKey:@"ary"];
   	[dict setValue:aryPath forKey:@"aryPath"];
   	BOOL dictFlag=[dict writeToFile:dictPath atomically:YES];
   	if(dictFlag)
   	{
   		dict=[NSMutableDictionary dictionaryWithContentsOfFile:dictPath];
   		NSLog(@"\ndictFromFile=\n%@",dict);
   	}
   	
   	
   	// *3> OCstr的序列化与反序列化
   	NSString * path= @"C:/Users/Administrator/Desktop/str.txt";
   	// 将OCstr按某种编码方式encode成bytes保存在NSData
   	NSData *data=[@"this is an NSData test!!\n" dataUsingEncoding:NSUTF8StringEncoding];
   	// 将bytes写入文件
   	BOOL strPathFlag=[fm createFileAtPath:path contents:data attributes:nil];
   	if(strPathFlag)
   	{
   		// 从文件读取bytes保存为NSData类型
		NSData *strData=[fm contentsAtPath:path];
		// 将bytes按某种解码方式decode成OCstr
		NSString *strFromData=[[[NSString alloc] initWithData:strData
		encoding:NSUTF8StringEncoding] autorelease];
		NSLog(@"\nstrFromData=%@",strFromData);   	
   	}
   	
   
   	
   	// *4> struct与NSValue的互相转换
   	Scores scores1={66.0,77.0,88.0},scores2={0},* scores3={0};
   	// 将struct包装成NSValue，@encode(Type)将struct类型转换成(char *)类型
   	NSValue *scoresVal=[NSValue valueWithBytes:&scores1 objCType:@encode(Scores)];
   	// 从NSValue中取出struct
   	[scoresVal getValue:&scores2];
   	NSLog(@"\nscoresValFromStruct=%@\nscores2FromNSValue=%@",scoresVal,NSStringFromScores(scores2));
   
   
   // *5> 将数据按照其在内存中的bytes写入文件，并将文件中的bytes读入内存
   	NSString * bytePath= @"C:/Users/Administrator/Desktop/byte.txt";
   	// 将struct按照其内存中的bytes保存到NSData对象
   	NSData *data2=[NSData dataWithBytes:&scores2 length:sizeof(Scores)];
   	// 将bytes写入文件
    BOOL bytePathFlag=[fm createFileAtPath:bytePath contents:data2 attributes:nil];
   	if(bytePathFlag)
   	{	
   		// 从文件读取bytes保存到NSData对象
   		NSData *data3=[fm contentsAtPath:bytePath];
   		// 取出NSData对象中的bytes，转换成struct
   		scores3=(Scores *)[data2 bytes];
   		NSLog(@"\nscores3FromNSData=%@",NSStringFromScores(*scores3));
   	}
   
   
    [pool drain];
    return 0;
} 


// 将Scores结构体转字符串
NSString * NSStringFromScores(Scores s)
{
	return [NSString stringWithFormat:
	@"{ mathScore=%.2f, engScore=%.2f, cScore=%.2f }",
	s.mathScore,s.engScore,s.cScore];
}