ios调试经验

程序开发的时候，总会遇到这样那样的bug。有些情况下打印日志比较方便，更多的时候需要依靠Debug工具。

XCode为我们集成了图形化的调试工具，也提供了命令行接口，所以调试起来还是比较方便的。

如上图，左侧是图形化界面，右侧是命令行接口。

常用命令

p   xxx ：如果xxx是Object，打印地址，否则打印value

po xxx：xxx必须是Object，打印对象的description

expr xxx=???：将变量xxx的值修改成???

breakpoint set -n "-[UIView setFrame:]" ：将断点设在某个方法上

breakpoint set --selector selectxxx：将断点设在某个selector上

watchpoint set variable xxx：设置变量断点，当变量被修改时会中断

watchpoint set expression -- xxx [-x byte_size]：设置内存区域断点，发生修改时会中断

异常断点：断点窗口左下角添加Add Exception Breakpoint，能在发生异常式断住

常见错误

EXC_BAD_ACCESS  内存访问错误

1、设置Enable Zombie Objects ，能够打印出一些有用信息

*** -[UIView superview]: message sent to deallocated instance 0xa081220

但有时候还不够，还想知道那个地址对应的对象是哪来的。需要再设置Malloc Stack。然后在命令行下执行malloc_history 线程号  内存地址

sudo malloc_history 1157 0x993baa0

就会打印出该地址对象的创建过程

malloc_history Report Version:  2.0Process:         DebugDemo [1157]Path:            /Users/minjieni/Library/Application Support/iPhone Simulator/7.0/Applications/0C40E6FA-9F86-462B-84E3-D480281EF48D/DebugDemo.app/DebugDemoLoad Address:    0x1000Identifier:      DebugDemoVersion:         ??? (???)Code Type:       X86 (Native)Parent Process:  debugserver [1158]Date/Time:       2013-10-11 22:53:17.117 +0800OS Version:      Mac OS X 10.8.4 (12E3200)Report Version:  7ALLOC 0x993baa0-0x993baff [size=96]: thread_1ea8a28 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __CFRunLoopRun | __CFRunLoopDoSources0 | __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ | _UIApplicationHandleEventQueue | -[UIApplication sendEvent:] | -[UIWindow sendEvent:] | -[UIWindow _sendTouchesForEvent:] | -[UIControl touchesEnded:withEvent:] | -[UIControl _sendActionsForEvents:withEvent:] | -[UIControl sendAction:to:forEvent:] | -[UIApplication sendAction:toTarget:fromSender:forEvent:] | -[UIApplication sendAction:to:from:forEvent:] | -[NSObject performSelector:withObject:withObject:] | -[ViewController gotoDetailViewController] | -[UIViewController presentViewController:animated:completion:] | -[UIViewController presentViewController:withTransition:completion:] | -[UIWindowController transition:fromViewController:toViewController:target:didEndSelector:animation:] | -[UIViewController _preferredInterfaceOrientationForPresentationInWindow:fromInterfaceOrientation:] | -[UIViewController shouldAutorotate] | -[UIViewController view] | -[UIViewController loadViewIfRequired] | -[DetailViewController viewDidLoad] | _objc_rootAlloc | class_createInstance | calloc | malloc_zone_calloc