#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {

super viewDidLoad];

#pragma mark ---写入字符串--------

//第一步:确定要存储文件夹的路径

NSString *documentPathStr = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0];

//第二步:确定要存储的数据 初始化一个字符串

NSString *str = @"Hello world";

//第三步:确定存放文件的路径,路径的终点是要存储数据的文件

NSString *strPath = [documentPathStr stringByAppendingPathComponent:@"str.txt"];

//第四步:写入文件(创建文件写入文件)

//atomically:YES:写入过程中断电时,会自动保存

[str writeToFile:strPath atomically:YES encoding:NSUTF8StringEncoding error:nil];

NSLog(@"%@",documentPathStr);

#pragma mark ---写入数组--------

//第二步:准备存储的数据

NSArray *arr = @[@"A",@"B"];

//第三步:存放位置

NSString *arrayPath = [documentPathStr stringByAppendingPathComponent:@"array.plist"];

//第四步:写入

[arr writeToFile:arrayPath atomically:YES];

#pragma mark ---写入字典--------

NSDictionary *dic = @{@"1":@"A",@"2":@"B"};

NSString *dicPath = [documentPathStr stringByAppendingPathComponent:@"dic.plist"];

[dic writeToFile:dicPath atomically:YES];

#pragma mark ---读取--------

//通过路径读取数据,使用StringWithContentsOfFile方法,在读取的时候,第一个参数表示读取文件的路径,第二个参数表示编码格式,第三个表示错误信息

NSString *newStr = [NSString stringWithContentsOfFile:strPath encoding:NSUTF8StringEncoding error:nil];

NSLog(@"%@",newStr);

NSArray *newArray = [NSArray arrayWithContentsOfFile:arrayPath];

NSLog(@"%@",newArray);

#pragma mark ---图片--------

//根据ImageNamed获取图片(会在缓存中存储一份,下次再获取同名图片的话直接从缓存中取出)  优点:快 只有第一次时慢  缺点:会浪费内存,如果只用一次的话这块内存就会浪费掉了

//UIImage *image = [UIImage imageNamed:@"1"];

//根据ContentOfFile获取图片:每一次都会从路径中读取,不会占用内存.如果该图片只使用一次的话 推荐使用ContentOfFile

//UIImage *image1 = [[UIImage alloc] initWithContentsOfFile:@"1"];

UIImage *image = [UIImage imageNamed:@"1"];

#pragma mark ---将UIImage类型对象转化成NSData类型---

 //NSData *data = UIImagePNGRepresentation(image);

//第一个参数:表示转哪个UIImage类型的对象

//第二个参数:压缩系数 越小压缩的越厉害

NSData *data = UIImageJPEGRepresentation(image, 1);

NSString *dataPath = [documentPathStr stringByAppendingPathComponent:@"data.png"];

[data writeToFile:dataPath atomically:YES];

UIImageView *imageView = [[UIImageView alloc] initWithImage:image];

[self.view addSubview:imageView];

#pragma mark ---将类型NSData对象转化成UIImage类型---

NSData *newData = [NSData dataWithContentsOfFile:dataPath];

UIImage *newImage = [[UIImage alloc] initWithData:newData];

NSLog(@"%@",newImage);

}

- (void)didReceiveMemoryWarning {

  [super didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end