ios本地存储篇

本地存储

本地存储将数据保存到本地，能够让程序的运行更加流畅。我们会经常用文件读写、NSUserDefaults、数据库。

.NSUserDefaults：用来保存应用程序设置和属性、用户保存的数据。用户再次打开程序或开机后这些数据仍然存在。NSUserDefaults可以存储的数据类型包括：NSData、NSString、NSNumber、NSDate、NSArray、NSDictionary。格式比较类似。

//获得document路径
+(NSString *)findDocumentPath{
    NSArray * paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString * value = [paths lastObject];
    return value;
}

//字符串的写入
+(BOOL)writeStringValue{
    
    NSString * str = @"hello";
    NSString * path = [WriteLocalModel findDocumentPath]; 
    NSString * realPath = [NSString stringWithFormat:@"%@/Hello.txt",path];
    NSError * error = Nil;
    BOOL result = [str writeToFile:realPath atomically:YES encoding:NSUTF8StringEncoding error:&error];
    return result;
}
//数据的写入
 +(BOOL)writeArrayValue{
    
    NSArray * arr  = [NSArray arrayWithObjects:@"1",@"2", nil];
    NSString * path = [WriteLocalModel findDocumentPath];
    NSString * realPath = [NSString stringWithFormat:@"%@/kity.txt",path];
    BOOL result = [arr writeToFile:realPath atomically:YES];
    return result;
}
//数据的写入
+(BOOL)writeDataValue{
    
    NSString * str = [NSString stringWithFormat:@"蜡笔小新"];
    NSData * data = [str dataUsingEncoding:NSUTF8StringEncoding];
    NSString * path = [WriteLocalModel findDocumentPath];
    NSString * realPath = [NSString stringWithFormat:@"%@/helloKity.txt",path];
    BOOL result = [data writeToFile:realPath atomically:YES];
    return result;
}

+(NSString *)readString{
    
    NSString * path = [WriteLocalModel findDocumentPath];
    NSString * realPath = [NSString stringWithFormat:@"%@/Hello.txt",path];
//    NSString * value = [[[NSString alloc] initWithContentsOfFile:realPath encoding:NSUTF8StringEncoding error:NULL] autorelease];
    NSString * value = [NSString stringWithContentsOfFile:realPath encoding:NSUTF8StringEncoding error:NULL];
    return value;
}

+(NSArray *)readArray{
    
    NSString * path = [WriteLocalModel findDocumentPath];
    NSString * realPath = [NSString stringWithFormat:@"%@/kity.txt",path];
//    NSArray * value = [NSArray arrayWithContentsOfFile:realPath];
    NSArray * value = [[[NSArray alloc] initWithContentsOfFile:realPath] autorelease];
    return value;
}

+(NSData *)readData{
    
    NSString * path = [WriteLocalModel findDocumentPath];
    NSString * realPath = [NSString stringWithFormat:@"%@/helloKity.txt",path];
//    NSData * value = [NSData dataWithContentsOfFile:realPath];
    NSData * value = [[NSData alloc] initWithContentsOfFile:realPath];
    
    return value;
}

//NSUserDefaults对plist的存储
+(void)userDefaultsWrite{
    
    [[NSUserDefaults standardUserDefaults] setObject:@"hellohellohello" forKey:@"a"];
    //同步存储
    [[NSUserDefaults standardUserDefaults] synchronize];
    
}

SQLite：采用SQLite数据库来存储数据。SQLite作为一中小型数据库，应用ios中，跟前三种保存方式相比，相对比较复杂一些。还是一步步来吧！
第一步：需要添加SQLite相关的库以及头文件：在项目文件的Build Phases下，找到Link Binary Library(ies)，添加libsqlite3.0.dylib（libsqlite3.dylib与前者的区别暂时不知，两者应该差不多）；在项目文件中头文件或者源文件中添加头文件#import "/usr/include/sqlite3.h"
第二步：开始使用SQLite：

+(NSArray *)findAllPerson{
    
    NSMutableArray * arr = [NSMutableArray array];
    //获得数据库指针
    sqlite3 * dbPoint = [DB openDataBase];
    
    //创建数据库替身
    sqlite3_stmt * stmt;
    
    //创建数据库语句并检查数据库语句的正确与否 -1是无限制
    int result = sqlite3_prepare(dbPoint, "select workername,workerid,workersex,workscore from Lanou", -1, &stmt, NULL);
    //判断数据库语句是否正确
    if (SQLITE_OK == result) {
        //执行数据库操作并判断是否有下一条数据
        while (sqlite3_step(stmt) == SQLITE_ROW) {
            //查询数据库当前行的第几列，其中第二个参数“0”代表数据库语句中得顺序。
            const unsigned char * workerName = sqlite3_column_text(stmt, 0);
            int workerId = sqlite3_column_int(stmt, 1);
            const unsigned char * workerSex = sqlite3_column_text(stmt, 2);
            float workerScore = sqlite3_column_double(stmt, 3);
            
            
            NSString * name = [NSString stringWithUTF8String:(const char *)workerName];
            NSString * sex = [NSString stringWithUTF8String:(const char *)workerSex];
            
            PeopleModel * model = [PeopleModel peopleModelWithWorkerId:workerId workerName:name workerSex:sex workerScore:workerScore];
            [arr addObject:model];
        }
    }
    //清除内存
    sqlite3_finalize(stmt);
    return arr;
}

+(PeopleModel *)findModelWithId:(NSInteger)workerId{
    
    //获得数据库指针
    sqlite3 * dbPoint = [DB openDataBase];
    
    //创建数据库替身
    sqlite3_stmt * stmt;
    
    //创建数据库语句并检查数据库语句的正确与否 -1是无限制
    int result = sqlite3_prepare(dbPoint, "select workerid,workername,workersex,workscore from Lanou where workerid = ?", -1, &stmt, NULL);
    //绑定sql语句中得问号
    sqlite3_bind_int(stmt, 1, workerId);
    
    if (SQLITE_OK == result) {
        //执行数据库操作并判断是否有下一条数据
        
        if (sqlite3_step(stmt) == SQLITE_ROW) {
            const unsigned char * workerName = sqlite3_column_text(stmt, 1);
            const unsigned char * workerSex = sqlite3_column_text(stmt, 2);
            float workerScore = sqlite3_column_double(stmt, 3);
            
            
            NSString * name = [NSString stringWithUTF8String:(const char *)workerName];
            NSString * sex = [NSString stringWithUTF8String:(const char *)workerSex];
            
            PeopleModel *  model = [PeopleModel peopleModelWithWorkerId:workerId workerName:name workerSex:sex workerScore:workerScore];
            
            sqlite3_finalize(stmt);
            return model;

        }
        
    }

    return Nil;
}

+(BOOL)addPerson:(PeopleModel *)model{
    //获得数据库指针
    sqlite3 * dbPoint = [DB openDataBase];
    
    //创建数据库替身
    sqlite3_stmt * stmt;
    
    //创建数据库语句并检查数据库语句的正确与否 -1是无限制
    int result = sqlite3_prepare(dbPoint, "insert into Lanou values(?,?,?,?)", -1, &stmt, NULL);
    
    //绑定sql语句中得问号
    sqlite3_bind_int(stmt, 1, model.workerId);
    sqlite3_bind_text(stmt, 2, [model.workerName UTF8String], -1, Nil);
    sqlite3_bind_text(stmt, 3, [model.workerSex UTF8String], -1, Nil);
    sqlite3_bind_double(stmt, 4, model.workerScore);
    if (SQLITE_OK == result) {
        if (sqlite3_step(stmt) == SQLITE_DONE){
            sqlite3_finalize(stmt);
            return YES;
        }else{
            return NO;
        }
    }
    return NO;

}


//page从一开始查询
+(NSArray *)findAllPersonWithPage:(NSInteger)page{
    
    NSInteger souceCount = 10 * (page - 1);
    
    NSMutableArray * arr = [NSMutableArray array];
    //获得数据库指针
    sqlite3 * dbPoint = [DB openDataBase];
    
    //创建数据库替身
    sqlite3_stmt * stmt;
    
    //创建数据库语句并检查数据库语句的正确与否 -1是无限制
    int result = sqlite3_prepare(dbPoint, "select * from Lanou limit ?,10", -1, &stmt, NULL);
    sqlite3_bind_int(stmt, 1, souceCount);
    
    
    //判断数据库语句是否正确
    if (SQLITE_OK == result) {
        //执行数据库操作并判断是否有下一条数据
        while (sqlite3_step(stmt) == SQLITE_ROW) {
            //查询数据库当前行的第几列，其中第二个参数“0”代表数据库语句中得顺序。
            const unsigned char * workerName = sqlite3_column_text(stmt, 1);
            int workerId = sqlite3_column_int(stmt, 0);
            const unsigned char * workerSex = sqlite3_column_text(stmt, 2);
            float workerScore = sqlite3_column_double(stmt, 3);
            
            
            NSString * name = [NSString stringWithUTF8String:(const char *)workerName];
            NSString * sex = [NSString stringWithUTF8String:(const char *)workerSex];
            
            PeopleModel * model = [PeopleModel peopleModelWithWorkerId:workerId workerName:name workerSex:sex workerScore:workerScore];
            [arr addObject:model];
        }
    }
    //清除内存
    sqlite3_finalize(stmt);
    return arr;
}