iOS CoreData 開發，ioscoredata開發

iOS CoreData 開發，ioscoredata開發

新年新氣象，曾經的妹子結婚了，而光棍的我決定書寫部落格~ 廢話結束。

本人不愛使用第三方的東東，喜歡原汁原味的官方版本，本次帶來CoreData資料存放區篇~

 

建立應用

勾上Use Core Data,不勾也行，後面再添加上去一樣的

點擊coredata檔案，look下

添加實體，點擊下面的Add Entity即可，或者通過菜單操作，效果一樣。

 

建立一個實體類

 

 

接著，產生代碼：

點擊Create NSManagedObject Subclass ....,然後選擇我們的User，產生代碼

 

寫代碼之前，先來點介紹吧，主要涉及到下面三個東東

1、Managed Object Model ， 理解成資料庫吧，儲存了Entity,就是你要儲存的東西

2、Persistent Store Coordinate， 理解成資料庫連接吧，裡面存放了資料存放區到具體的檔案等等資訊

3、Managed Object Context， 資料內容，基本上所有的操作都是通過這個的。

 

下面進入寫代碼狀態：

 上面三個對象，一個不可少，所以，先來初始化之類的操作吧

 

1 ///定義三個屬性2 3 4 @property(strong,nonatomic) NSManagedObjectModel *cdModel;5 @property(strong,nonatomic) NSManagedObjectContext *cdContext;6 @property(strong,nonatomic) NSPersistentStoreCoordinator *cdCoordinator;

 1 - (NSManagedObjectModel *)cdModel 2 { 3     if(!_cdModel) 4     { 5         _cdModel = [NSManagedObjectModel mergedModelFromBundles:nil]; 6     } 7      8     return _cdModel; 9 }10 11 - (NSPersistentStoreCoordinator *)cdCoordinator12 {13     if(!_cdCoordinator)14     {15         //find the database16         NSString *dirPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:DBNAME];17         NSURL *dbPath = [NSURL fileURLWithPath:dirPath];18         NSError *err;19         _cdCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.cdModel];20         if(![_cdCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:dbPath options:nil error:&err])21         {22             NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);23         }24         dirPath = nil;25         dbPath = nil;26     }27     return _cdCoordinator;28 }29 30 - (NSManagedObjectContext *)cdContext31 {32     if(!_cdContext)33     {34         _cdContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];35         [_cdContext setPersistentStoreCoordinator:self.cdCoordinator];36     }37     return _cdContext;38 }

下面進行CRUD操作

 1 - (void)insertToDB:(NSString *)username password:(NSString *)password 2 { 3     User *u = (User *)[NSEntityDescription insertNewObjectForEntityForName:TBNAME inManagedObjectContext:self.cdContext]; 4     u.username = username; 5     u.password = password; 6     NSError *err; 7     if(![self.cdContext save:&err]) 8     { 9         NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);10     }11 }12 13 - (void)readFromDb14 {15     NSFetchRequest *fetch = [[NSFetchRequest alloc] init];16     NSEntityDescription *entity = [NSEntityDescription entityForName:TBNAME inManagedObjectContext:self.cdContext];17     [fetch setEntity:entity];18     NSError* err;19     NSArray *results = [self.cdContext executeFetchRequest:fetch error:&err];20     if(err)21     {22         NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);23         return;24     }25     [results enumerateObjectsUsingBlock:^(User  *_Nonnull user, NSUInteger idx, BOOL * _Nonnull stop) {26         NSLog(@"----%@   %@",user.username,user.password);27     }];28 }

好的，來測試下：

 

算了，時間來不及了，要睡覺了，就不囉嗦了，下面是完整代碼

  1 //  2 //  ViewController.m  3 //  CoreDataTest  4 //  5 //  Created by winter on 16/2/14.  6 //  Copyright © 2016年 winter. All rights reserved.  7 //  8   9 #import "ViewController.h" 10 #import <CoreData/CoreData.h> 11 #import "User.h" 12  13 /// define database name 14 #define DBNAME @"CoreDataTest.sqlite" 15 /// define entity 16 #define TBNAME @"User" 17  18  19 @interface ViewController () 20 { 21      22 } 23 ///定義三個屬性 24  25  26 @property(strong,nonatomic) NSManagedObjectModel *cdModel; 27 @property(strong,nonatomic) NSManagedObjectContext *cdContext; 28 @property(strong,nonatomic) NSPersistentStoreCoordinator *cdCoordinator; 29  30  31 @end 32  33 @implementation ViewController 34  35 #pragma mark - 實現三個屬性的getter Method 36  37 - (NSManagedObjectModel *)cdModel 38 { 39     if(!_cdModel) 40     { 41         _cdModel = [NSManagedObjectModel mergedModelFromBundles:nil]; 42     } 43      44     return _cdModel; 45 } 46  47 - (NSPersistentStoreCoordinator *)cdCoordinator 48 { 49     if(!_cdCoordinator) 50     { 51         //find the database 52         NSString *dirPath = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:DBNAME]; 53         NSURL *dbPath = [NSURL fileURLWithPath:dirPath]; 54         NSError *err; 55         _cdCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:self.cdModel]; 56         if(![_cdCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:dbPath options:nil error:&err]) 57         { 58             NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason); 59         } 60         dirPath = nil; 61         dbPath = nil; 62     } 63     return _cdCoordinator; 64 } 65  66 - (NSManagedObjectContext *)cdContext 67 { 68     if(!_cdContext) 69     { 70         _cdContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType]; 71         [_cdContext setPersistentStoreCoordinator:self.cdCoordinator]; 72     } 73     return _cdContext; 74 } 75  76  77 #pragma mark - crud 78 - (void)insertToDB:(NSString *)username password:(NSString *)password 79 { 80     User *u = (User *)[NSEntityDescription insertNewObjectForEntityForName:TBNAME inManagedObjectContext:self.cdContext]; 81     u.username = username; 82     u.password = password; 83     NSError *err; 84     if(![self.cdContext save:&err]) 85     { 86         NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason); 87     } 88 } 89  90 - (void)readFromDb 91 { 92     NSFetchRequest *fetch = [[NSFetchRequest alloc] init]; 93     NSEntityDescription *entity = [NSEntityDescription entityForName:TBNAME inManagedObjectContext:self.cdContext]; 94     [fetch setEntity:entity]; 95     NSError* err; 96     NSArray *results = [self.cdContext executeFetchRequest:fetch error:&err]; 97     if(err) 98     { 99         NSLog(@"Error %@  %@",err.localizedDescription,err.localizedFailureReason);100         return;101     }102     [results enumerateObjectsUsingBlock:^(User  *_Nonnull user, NSUInteger idx, BOOL * _Nonnull stop) {103         NSLog(@"----%@   %@",user.username,user.password);104     }];105 }106 107 108 - (void)viewDidLoad {109     [super viewDidLoad];110     // Do any additional setup after loading the view, typically from a nib.111     [self insertToDB:@"wang" password:@"password"];112     113 }114 115 - (void)viewDidAppear:(BOOL)animated116 {117     [super viewDidAppear:animated];118     [self readFromDb];119 }120 121 - (void)didReceiveMemoryWarning {122     [super didReceiveMemoryWarning];123     // Dispose of any resources that can be recreated.124 }125 126 @end