在iOS中一般將數(shù)據(jù)寫(xiě)入本地, 可以分為兩大類第一類是簡(jiǎn)單對(duì)象 另一類是復(fù)雜對(duì)象 對(duì)于簡(jiǎn)單對(duì)象 我們直接進(jìn)行寫(xiě)入和獲取就可以 對(duì)于復(fù)雜對(duì)象 我們利用的是歸檔和反歸檔(歸檔和反歸檔是對(duì)于復(fù)雜對(duì)象的存儲(chǔ)和獲取)

要將數(shù)據(jù)寫(xiě)入本地 首先我們先來(lái)了解一下沙盒(SandBox)
沙盒中包含三個(gè)文件夾:

1. Document(文件文檔 用來(lái)給用戶存儲(chǔ)數(shù)據(jù)的文件夾)
2. Library(資源 程序員用這個(gè)文件夾存儲(chǔ)數(shù)據(jù)信息)
   Library文件夾又包含兩個(gè)文件夾:
   CaChes(緩存數(shù)據(jù)的文件夾)
   Preferences(存儲(chǔ)用戶信息的 例如; NSUserDefaults)
3. tmp(臨時(shí)目錄 下載的臨時(shí)文件)

沙盒是由以上三個(gè)文件夾組成的 其中Document文件夾就是用戶用來(lái)存儲(chǔ)數(shù)據(jù)用的 用戶將可以將數(shù)據(jù)存放到這個(gè)文件夾里

下面我們來(lái)用沙盒存儲(chǔ)數(shù)據(jù):

1. 簡(jiǎn)單數(shù)據(jù)的存儲(chǔ)(字符串 數(shù)組 字典 NSData)
   // 字符串的存儲(chǔ)
   // 1. 創(chuàng)建沙盒路徑
   NSArray *pathArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
   // 2. 創(chuàng)建一個(gè)字符串 將這個(gè)字符串存到 沙盒中
   NSString *str = @"離別是今晚的康橋, I/O file";
   // 3. 拼接字符串路徑
   NSString *path = [[pathArray firstObject] stringByAppendingPathComponent:@"poet.txt"];
   NSError *error = nil;
   // 4. 將字符串寫(xiě)入本地
   BOOL isSuc = [str writeToFile:path atomically:YES encoding:NSUTF8StringEncoding error:&error];
   if (isSuc) {
   NSLog(@"存儲(chǔ)失敗");
   } else {
   NSLog(@"存儲(chǔ)成功");
   }
   // 5. 讀取字符串
   NSError *readError = nil;
   NSString *readStr = [NSString stringWithContentsOfFile:path encoding:NSUTF8StringEncoding error:&readError];
   NSLog(@"%@", readStr);

   // 將數(shù)組寫(xiě)入本地
   // 這里 我們就用之前創(chuàng)建的沙盒來(lái)做就可以
   NSArray *array = @[@"十年", @"陀飛輪", @"十面埋伏", @"遙遠(yuǎn)的她"];
   // 拼接數(shù)組路徑
   NSString *arrayPath = [[pathArray firstObject]stringByAppendingPathComponent:@"musicName.plist"];
   // 將數(shù)組寫(xiě)入本地
   BOOL isSuce = [array writeToFile:arrayPath atomically:YES];
   if (isSuce) {
    NSLog(@"存儲(chǔ)失敗");
   } else {
    NSLog(@"存儲(chǔ)成功");
   }
   // 讀取數(shù)組
   NSArray *array1 = [NSArray arrayWithContentsOfFile:arrayPath];
   NSLog(@"%@", array1);
   
   // 字典寫(xiě)入本地
   NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:@"十年", @"陳奕迅", @"大地", @"beyond", @"可樂(lè)", @"趙", nil];
   // 拼接字典路徑
   NSString *dicPath = [[pathArray firstObject] stringByAppendingPathComponent:@"music.plist"];
   // 將字典寫(xiě)入本地
   BOOL isDic = [dic writeToFile:dicPath atomically:YES];
   if (isDic) {
    NSLog(@"存儲(chǔ)成功");
   } else {
    NSLog(@"存儲(chǔ)失敗");
   }
   // 讀出字典
   NSDictionary *secDic = [NSDictionary dictionaryWithContentsOfFile:dicPath];
   NSLog(@"%@", secDic);
   
   // 將NSData類型寫(xiě)入本地
   UIImage *image = [UIImage imageNamed:@"u=881185622,577705802&fm=206&gp=0"];
   // 需要將圖轉(zhuǎn)化為二進(jìn)制(NSData類型)
   // UIImageJPEGRepresentation  UIImagePNGRepresentation(<#UIImage * _Nonnull image#>)
   NSData *imageData = UIImageJPEGRepresentation(image, 0.1);
   // 拼接路徑
   NSLog(@"%@", imageData);
   NSString *dataPath = [[pathArray firstObject] stringByAppendingPathComponent:@"image.a"];
   // 寫(xiě)入本地
   BOOL isData = [imageData writeToFile:dataPath atomically:YES];
   if (isData) {
    NSLog(@"寫(xiě)入成功");
   } else {
    NSLog(@"寫(xiě)入失敗");
   }
   // 讀取NSData
   NSData *newData = [NSData dataWithContentsOfFile:dataPath];
   UIImage *newImage = [UIImage imageWithData:newData];
   NSLog(@"%@", newImage);
   

總結(jié)一下 通過(guò)上面將數(shù)據(jù)寫(xiě)入本地的例子可以看出 簡(jiǎn)單數(shù)據(jù)寫(xiě)入本地主要分為這幾步:
(1) 創(chuàng)建沙盒路徑
(2) 創(chuàng)建一個(gè)你要存儲(chǔ)的對(duì)象
(3) 拼接路徑
(4) 寫(xiě)入本地
(5) 從本地讀取數(shù)據(jù)

下面 來(lái)說(shuō)一下怎么將復(fù)雜對(duì)象存儲(chǔ)到本地 所謂復(fù)雜對(duì)象就是指 在實(shí)際應(yīng)用中 我們用到的model數(shù)據(jù) 將復(fù)雜數(shù)據(jù)存儲(chǔ)到本地要用到歸檔 將復(fù)雜數(shù)據(jù)從本地中讀出來(lái)要用到反歸檔
1 我們創(chuàng)建一個(gè)自定義的類(繼承與 NSObject)

#import <Foundation/Foundation.h>
// 1. 將需要?dú)w檔的類  簽訂協(xié)議 簽訂   NSCoding協(xié)議         

@interface Book : NSObject   <NSCoding>

@property (nonatomic, copy)   NSString *bookName;
@property (nonatomic, copy) NSString *bookPrice;
@property (nonatomic, copy) NSString *writer;
@property (nonatomic, copy) NSString *bookAddress;
@property (nonatomic, copy) NSString *bookType;

@end


#import "Book.h"

@implementation Book
// 2. 簽訂協(xié)議后 必須實(shí)現(xiàn) 下面兩個(gè)方法
// 初始化是 讀取數(shù)據(jù)的
- (instancetype)initWithCoder:(NSCoder *)aDecoder {
self = [super init];
if (self) {
    _bookName = [aDecoder decodeObjectForKey:@"bookName"];
    _bookPrice = [aDecoder decodeObjectForKey:@"bookPrice"];
    _writer = [aDecoder decodeObjectForKey:@"writer"];
    _bookAddress = [aDecoder decodeObjectForKey:@"bookAddress"];
    _bookType = [aDecoder decodeObjectForKey:@"bookType"];
}
return self;
}
// 寫(xiě)入數(shù)據(jù)的方法 賦值
- (void)encodeWithCoder:(NSCoder *)aCoder {
[aCoder encodeObject:_bookName forKey:@"bookName"];
[aCoder encodeObject:_bookPrice forKey:@"bookPrice"];
[aCoder encodeObject:_writer forKey:@"writer"];
[aCoder encodeObject:_bookAddress forKey:@"bookAddress"];
[aCoder encodeObject:_bookType forKey:@"bookType"];
}



@end


Book *book = [Book new];
book.bookName = @"傲慢與偏見(jiàn)";
book.bookPrice = @"18.5";
book.writer = @"josejjs";
book.bookType = @"story";
book.bookAddress = @"English";

NSString *bookPath = [[pathArray firstObject] stringByAppendingPathComponent:@"book.plist"];
BOOL isBook = [NSKeyedArchiver archiveRootObject:book toFile:bookPath];
if (isBook) {
    NSLog(@"寫(xiě)入成功");
} else {
    NSLog(@"寫(xiě)入失敗");
}

// 2. 反歸檔(取出對(duì)象 反歸檔走的是初始化)
Book *book1 = [NSKeyedUnarchiver unarchiveObjectWithFile:bookPath];
NSLog(@"%@", book1.bookName);