pragma mark ------- * 简单的文件读写 ------
ios提供四种类型可以直接进行文件存取
- NSString(及子类)
- NSArray(及子类)
- NSDictionary(及子类)
- NSData(及子类)
#import "ViewController.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
#pragma mark ---字符串写入--------
//第一步:获取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(会创建一个临时文件, 知道临时文件写入完成, 再整体导入Document(保证数据的原子性))
BOOL result = [str writeToFile:strPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
if (result) {
NSLog(@"写入成功%@",documents);
}else{
NSLog(@"失败了");
}
NSLog(@"%@",documentPathStr);
#pragma mark ---字符串读取--------
//参数一: 文件路径
//参数二: 编码, 枚举值
//参数三: 错误信息, nil
NSString *newStr = [NSString stringWithContentsOfFile:strPath encoding:4 error:nil];
NSLog(@"newStr == %@", newStr);
#pragma mark ---数组写入--------
//第二步:准备存储的数据
NSArray *arr = @[@"A",@"B"];
//第三步:存放位置
SString *arrayPath = [documentPathStr stringByAppendingPathComponent:@"array.plist"];
//第四步:写入
[arr writeToFile:arrayPath atomically:YES];
#pragma mark ---数组读取--------
NSArray *Newarray = [NSArray arrayWithContentsOfFile:arrayPath];
NSLog(@"%@", Newarray);
#pragma mark ---字典写入--------
NSDictionary *dic = @{@"1":@"A",@"2":@"B"};
NSString *dicPath = [documentPathStr stringByAppendingPathComponent:@"dic.plist"];
[dic writeToFile:dicPath atomically:YES];
#pragma mark ---字典读取--------
//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```
