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Interface & Implementation
@interface and @implementation are the first things you learn about when you start Objective-C:
@interface...@end
@implementation...@end
What you don't learn about until later on, are categories and class extensions.
Categories allow you to extend the behavi ...
NSPredicate is a Foundation class that specifies how data should be fetched or filtered. Its query language, which is like a cross between a SQL WHERE clause and a regular expression, provides an expressive, natural language interface to define logical conditions on which a collection is searched. ...
NSFileManager is Foundation's high-level API for working with file systems. It abstracts Unix and Finder internals, providing a convenient way to create, read, move, copy, and delete files & directories on local or networked drives, as well as iCloud ubiquitous containers.
File systems are a c ...
可以从数据库中的系统表 sysobjects 得到想要的数据表信息，具体SQL语句如下：
查看数据库中表名：
select name from sysobjects where type = 'U';
由于系统表sysobjects保存的都是数据库对象,其中type表示各种对象的类型，具体包括:
U = 用户表
S = 系统表
C = CHECK 约束
D = 默认值或 DEFAULT 约束
F = FOREIGN KEY 约束
L = 日志
FN = 标量函数
IF = 内嵌表函数
P =
当把应用程序从模拟器删除（长按AppIcon，图标晃动，出现叉号，点击叉号。点击主屏幕按钮就不晃动了）之后，再次运行应用程序后，Stop按钮就变灰色，应用程序停止运行，只有当点击模拟器上的图标才能继续。
这是因为点击了Clean，删除后直接运行就不会出现这个问题
一旦Clean，那么重启模拟器就好了
这是由于旋转时没有定位屏幕的位置，我们可以写一个旋转时的方法：
-(void)rotateToInterfaceOrientation:(UIInterfaceOrientation)toInterfaceOrientation
{
switch(toInterfaceOrientation)
{
case UIInterfaceOrientationLandscapeLeft:
self.view.transform=CGAffineTransformMakeRotation(3.1415926*(-90));//向右旋转 ...
Q: My application saves data to the application's bundle, which works fine in the iPhone Simulator. However, when I run on a device, my data cannot be saved. What's going on?A: The different behaviors you are seeing are due to differences between the iPhone Simulator and the actual device. In the s ...
开发环境使用的是目前为止最新的稳定版软件：Mac OS X Lion 10.7 + Xcode 4.1
目前Xcode 4.2 Preview版也已经发布，据说其修改方法跟4.1非常类似，只改动了一行代码，请参看参考文章的第二篇。本文仍以4.1版本为例。
更新：现在Xcode 4.2正式版和iOS 5均已发布，下面补充上4.2的修改方法。（2011-10-24）
各步骤会标明版本，比如（Xcode4.1请执行）和（Xcode4.2请执行），4.2.1的修改方法与4.2完全相同
未标明的步骤为两个版本均需执行的步骤！
更新：现在Xcode 4.3已发布，修改方法类似，Xcode ...
I've been on a search for a really good Sqlite Admin tool since I started iPhone programming a year ago. I've been mainly using the Firefox Plugin 80-90% or the time and Sqlite Administrator the rest of the time. I decided to do some more searching over the last couple of days and here's my repor ...
If you go into the UIKit_Framework and look at the NSNibDeclarations.h header file, you’ll see that they’re defined like this: macros(宏)
#define IBAction void
#define IBOutlet
#define IBOutletCollection（ClassName）
Confused? These two keywords do absolutely nothing as far as th ...
revalidate()方法并不是马上改变组件大小,而是标记该组件需要改变大小,这样就避免了多个组件都要改变大小时带来的重复计算,在javax.swing.JComponent中定义的。
validate()方法一旦被调用就立刻改变该容器内所有组件的大小在java.awt.Container中定义的。
首先要设置默认关闭操作为：什么也不做setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);然后添加Window监听
this.addWindowListener(new WindowListener()
{
public void windowClosing(WindowEvent we)
{
int option = JOptionPane.showConfirmDialog(null,"是否保存?","保 存", ...
一、C语言中可变参数列表函数写法:1.导入头文件: #include<stdarg.h>2.声明一个列表宏：va_list arg;3. 用宏va_start将该变量初始化为一个参数列表。作用是将调用时传递的参数列表复制到va_list变量中,并指明开始的参数。va_start()有两个参数：（va_list列表变量，紧挨着省略号前的参数）4.va_arg(va_list列表变量，参数类型)，每执行一次，就依次向下获得一个参数5.va_end(arg) 释放变量列表空间
#include<stdio.h>
#include<stdarg.h>
int ...