一.performSelector调用和直接调用区别 下面两段代码都在主线程中运行,我们在看别人代码时会发现有时会直接调用,有时会利用performSelector调用,今天看到有人在问这个问题,我便做一下总结, [delegate imageDownloader:self didFinishWithImage:image]; [delegate performSelector:@selector(imageDownloader:didFinishWithImage:)withObject:se

instancesRespondToSelector与respondsToSelector的区别   Test1.h @interface Test1 : NSObject - (void)objectFun; + (void)classFun; @end Test1.m @implementation Test1 - (void)objectFun { NSLog(@"object function"); } + (void)classFun { NSLog(@"class

Something you need to perform after RedHat 6.x installed YUM Repos % yum update % rpm -Uvh http://download.fedoraproject.org/pub/epel/6/x86_64/epel-release-6-8.noarch.rpm % rpm -Uvh http://rpms.famillecollet.com/enterprise/remi-release-6.rpm Developm

今天突然遇到这个问题,其实昨天下班的时候就已经有这个问题了, 就是先进入一个画页,然后再快速离开这个画页再进入其他画页就出现这个错误 了 找了好久也没有找出问题来,一开始以为是网络任务没有cancel掉,试了下好像又好了. 再把removeDataObser之类的,好像又好了. 最后过了一会儿,真的是必现.后面发现是设置了一个代理,但是没有实现这个代理方法,真是笑死人啊. 照理说一看 respondsToSelector,就是调用代理方法前判断代理有没有遵守这个协议实现这个方法什么的, 然后就应

public class ArgsTest { private List <Object> args; private ArgsTestCheckPoint checkPoint; public enum ArgsTestCheckPoint { IS_NAME_CORRECT,IS_PASSWORD_CORRECT } ArgsTest(ArgsTestCheckPoint checkPoint, Object ...objs) { this.checkPoint=checkPoint; f

Option 1: You can afford deleting the row In other words, you don't have foreign key, or if you have them, your SQLite engine is configured so that there no are integrity exceptions. The way to go is INSERT OR REPLACE. If you are trying to insert/upd

HowTo  Perform the spatial selection 'Share a line segment with' using ArcObjects Article ID: 26528 Software:  ArcGIS - ArcEditor 8.1, 8.1.2, 8.2, 8.3 ArcGIS - ArcInfo 8.1, 8.1.2, 8.2, 8.3 ArcGIS - ArcView 8.1, 8.1.2, 8.2, 8.3 Platforms:  Windows NT

PARAMETERS p_sub(40) TYPE c. DATA fssub(40) TYPE c. fssub = p_sub. TRY.     PERFORM (fssub) IN PROGRAM ydemo_rick_a. " IF FOUND.   CATCH cx_sy_dyn_call_illegal_form.     WRITE: 'The routine', p_sub COLOR 3, 'is not exist!'. ENDTRY. *&------------

-(BOOL) respondsToSelector: selector 用来判断是否有以某个名字命名的方法(被封装在一个selector的对象里传递)

You can do Select, Cut, Copy and Paste operations on text items in Oracle Forms using Select_All, Cut_Region, Copy_Region and Paste_Region commands through right click popup menu.   In this example I created a popup menu which is associated with the

发现对象是否响应消息 要发现一个对象是否响应一则消息,请在该对象上调用 respondsToSelector: 方法.应用程序代码通常验证一个对象响应一则消息后,才将消息发送给该对象. if ([item respondsToSelector:@selector(setState:)]){ [item setState:[self.arcView.font isBold] ?NSOnState :NSOffState]; } respondsToSelector: 方法将选择器视为其参数.选择器

做项目到最后整合的时候测试的时候发现  切换tab更换fragment的时候抛出了这个异常,根据异常信息Can not perform this action after onSaveInstanceState, 定位到: FragmentManager manager = getSupportFragmentManager(); FragmentTransaction transaction = manager .beginTransaction(); transaction .replace

java.lang.RuntimeException: Unable to resume activity {com.tongyan.nanjing.subway/com.tongyan.structure.ui.act.InsideTaskAct}: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState at android.app.ActivityThread.perfor

今天使用Fragment的时候,出现了这个错误 IllegalStateException: Can not perform this action after onSaveInstanceState: E/AndroidRuntime(12747): Caused by: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState at android.support.v4.app

1.前一天安装号db2后,做了如下处理: ************************************************************ 修改 /etc/sudoers 文件,找到下面一行,把前面的注释(#)去掉 ## Allows people in group wheel to run all commands%wheel    ALL=(ALL)    ALL 然后修改用户,使其属于root组(wheel),命令如下: #usermod -g root db2in

今天使用Fragment的时候,出现了这个错误 IllegalStateException: Can not perform this action after onSaveInstanceState: E/AndroidRuntime(12747): Caused by: java.lang.IllegalStateException: Can not perform this action after onSaveInstanceState at android.support.v4.app

这个问题在stackoverflow上面有过讨论: Can not perform pod install under el capitan (15A279b) 被采纳的答案为:sudo gem install -n /usr/local/bin cocoapods

今天做项目中的支付宝功能,是在fragment中做的,在支付成功后,想切换到支付成功的页面. 结果就报错了IllegalStateException: Can not perform this action after onSaveInstanceState: 在网上找了下解决方案,将commit改成了 commitAllowingStateLoss()就没问题了,贴出原帖地址http://www.ablanxue.com/prone_7000_1.html,参考. 今天使用Fragment的时

- (BOOL)respondsToSelector:(SEL)aSelector; 用来判断是否有以某个名字命名的方法 +(BOOL) instancesRespondToSelector: selector 用来判断实例是否有以某个名字命名的方法. 和上面一个不同之处在于, 前面这个方法可以用在实例和类上,而此方法只能用在类上.

-(BOOL) isKindOfClass: classObj 用来判断是否是某个类或其子类的实例 -(BOOL) isMemberOfClass: classObj 用来判断是否是某个类的实例 -(BOOL) respondsToSelector: selector 用来判断是否有以某个名字命名的方法(被封装在一个selector的对象里传递) +(BOOL) instancesRespondToSelector: selector 用来判断实例是否有以某个名字命名的方法. 和上面一个不同之处