iOS学习笔记整理4

整理笔记:

1、alt + 单机 更改距离 (上下左右)

2、class 代表与谁管关联的意思

3、block 在arc 中 单独释放 block _release

4、UIPickerView  视图选择器的使用

5、数据库使用：

a、NSString *douPath =[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)lastObject];

NSString *dbPath = [douPath stringByAppendingPathComponent:@"teachers.sqlite”];

//创建数据库

db = [FMDatabase databaseWithPath:dbPath];

b、创建： NSString *createTableSql = [NSString stringWithFormat:@"create table if not exists teacher (id integer primary key autoincrement,name text,address text,age integer,salary integer)"];

BOOL result =[db executeUpdate:createTableSql] ;

c、添加：NSString *insertSql = [NSString stringWithFormat:@"insert into teacher(name,address,age,salary)values('%@','%@','%ld','%ld')",teacher.name,teacher.address,teacher.age,teacher.salary];

BOOL result =[db executeUpdate:insertSql];

d、查询：NSString *selectSql = [NSString stringWithFormat:@"select * from teacher order by salary desc"];//asc 升序 ；  desc 降序

//执行查询

FMResultSet *set =[db executeQuery:selectSql];

while ([set next]) {

Teacher *tea = [[Teacher alloc]init];

tea.name = [set stringForColumn:@"name"];

tea.address = [set stringForColumn:@"address"];

tea.age = [set intForColumn:@"age"];

tea.salary = [set intForColumn:@"salary"];

[array addObject:tea];

}

e、更新：NSString *updeSql = [NSString stringWithFormat:@"update teacher set age = '40' where age = '31'"];

BOOL result =[db executeUpdate:updeSql];

f、删除： NSString *deleteSql = [NSString stringWithFormat:@"delete from teacher where salary = '700'"];

BOOL result =[db executeUpdate:deleteSql];