简单对象写入文件

#pragma mark 写入文件

//简单对象写入文件---------------->字符串、数组、字典、图片(才怪，是把图片转换成的NSData对象)

//1.字符串

NSString *incantation =
@"yi hu shi ";

NSString *homePath =
NSHomeDirectory();

homePath = [homePath
stringByAppendingString:@"/hh.txt"];

//NO:不安全，会中断。

//AllowLossy允许丢失碎片。

//ExternalRepresentation按字节转换，一个字节也不能丢失。

[incantation writeToFile:homePath
atomically:YES
encoding:NSStringEncodingConversionExternalRepresentation
error:nil];

NSLog(@"%@",homePath);

//从文件获取字符串

NSString *result = [NSString
stringWithContentsOfFile:homePath encoding:NSStringEncodingConversionExternalRepresentation
error:nil];

NSLog(@"%@",result);

//2、数组写入文件

NSArray *array =
@[@"you",@"are",@"you"];

NSString *path = NSHomeDirectory();

path = [path stringByAppendingString:@"hitu"];

//写入

[array writeToFile:path
atomically:YES];

NSLog(@"%@",path);

//读取

NSArray *resultArray = [NSArray
arrayWithContentsOfFile:path];

NSLog(@"%@",resultArray);

//3、字典写入文件

NSDictionary *dictionary =
@{

@"yiyi":@"huhu",

@"yoyo":@"kiki"

};

NSString *path = NSHomeDirectory();

path = [path stringByAppendingString:@"/oppo.txt"];

//写入
[dictionary
writeToFile:path atomically:YES];

NSLog(@"%@",path);

//读取

NSDictionary *dict = [NSDictionary
dictionaryWithContentsOfFile:path];

NSLog(@"%@",dict);

//4、图片是以NSData写入文件

UIImage *image = [UIImage
imageNamed:@"background.png"];

//0-1之间的，1是原封不动的大小

NSData *data =
UIImageJPEGRepresentation(image, 0.5);

NSString *path = NSHomeDirectory();

path = [path stringByAppendingString:@"/image"];

//写入

[data writeToFile:path
atomically:YES];

NSLog(@"%@",path);

//读取

NSData *resultData = [NSData
dataWithContentsOfFile:path];

UIImage *resultImage = [UIImage
imageWithData:resultData];

[_imageView
setImage:resultImage];