《精通iOS开发·第六版》数据持久化基础知识之对象归档持久化

《精通iOS开发·第六版》数据持久化基础知识之对象归档持久化

1、BIDViewController.h文件

#import "BIDViewController.h"#import "BIDFourLines.h"static NSString *const kRootKey = @"kRootKey";@interface BIDViewController ()@property(strong,nonatomic)IBOutletCollection(UITextField) NSArray *lineFields;@end@implementation BIDViewController- (void)viewDidLoad {    [super viewDidLoad];    //视图加载完成之后(通常是从nib文件加载)，做一些额外的设置    NSString *filePath = [self dataFilePath];    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {        NSData *data = [[NSMutableData alloc] initWithContentsOfFile:filePath];        NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];        BIDFourLines *fourLines = [unarchiver decodeObjectForKey:kRootKey];        [unarchiver finishDecoding];        for (int i=0; i<4; i++) {            UITextField *theField = self.lineFields[i];            theField.text = fourLines.lines[i];        }    }    UIApplication *app = [UIApplication sharedApplication];    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(applicationWillResignActive:) name:UIApplicationWillResignActiveNotification object:app];    // Do any additional setup after loading the view from its nib.}-(NSString *)dataFilePath{    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);    NSString *documentsDirectory = [paths objectAtIndex:0];    return  [documentsDirectory stringByAppendingPathComponent:@"data.archive"];}-(void)applicationWillResignActive:(NSNotification *)notification{    NSString *filePath = [self dataFilePath];    BIDFourLines *fourLines = [[BIDFourLines alloc] init];    fourLines.lines = [self.lineFields valueForKey:@"text"];    NSMutableData *data = [[NSMutableData alloc] init];    NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];    [archiver encodeObject:fourLines forKey:kRootKey];    [archiver finishEncoding];    [data writeToFile:filePath atomically:YES];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end

2、BIDViewController.xib

3、BIDFourLines.h文件

#import <Foundation/Foundation.h>@interface BIDFourLines : NSObject<NSCoding,NSCopying>@property(copy,nonatomic)NSArray *lines;@end

4、BIDFourLines.m文件

#import "BIDFourLines.h"static NSString *const kLinesKey = @"kLinesKey";@implementation BIDFourLines#pragma mark -Coding-(id)initWithCoder:(NSCoder *)aDecoder{    self = [super init];    if (self) {        self.lines = [aDecoder decodeObjectForKey:kLinesKey];    }    return self;}-(void)encodeWithCoder:(NSCoder *)aCoder{    [aCoder encodeObject:self.lines forKey:kLinesKey];}#pragma mark -Copying-(id)copyWithZone:(NSZone *)zone{    BIDFourLines *copy = [[[self class] allocWithZone:zone] init];    NSMutableArray *linesCopy = [NSMutableArray array];    for (id line in self.lines) {        [linesCopy addObject:[line copyWithZone:zone]];    }    copy.lines = linesCopy;    return copy;}@end

注意：如下图：


lineFields与XIB中的四个文本输入框链接