Basic debugging using logging for iOS apps

文章目录

• 前言

• I 、 DEBUG 宏的应用

•  

  • 1.1 发布模式关闭NSLog

• II、 NSLog调试技巧

•  

  • 2.1 Where to find NSLog's output

  • 2.2 Improved logging in Objective-C

  • 2.1 Objective-C's boxing capability (`装箱`快速构造数字对象)

  • 2.2 知识补充：装箱和拆箱

• see also

•  

  • Log facility 和level的关系

  • 常见的日志文件

  • 配置【生成/存储日志】策略: `vim /etc/rsyslog.conf`

  • 配置IP

  •  

 

 

 

前言

 

 

今天周末时间关系，此文只完成了部分内容，后续完整内容请移步到博客（kunnan.blog.csdn.net）

• 本文demo（请到博客看链接：kunnan.blog.csdn.net）

I 、 DEBUG 宏的应用

• 应用场景：区分调试模式和发布模式进行特殊处理

• 自定义preprocessor macro：

The DEBUG preprocessor macro setting in an Xcode project

1.1 发布模式关闭NSLog

//调试模式
#ifdef DEBUG
#define NSLog(...)     NSLog(__VA_ARGS__)
#define KisDebug 1

//#define NSLog(fmt, ...) NSLog((@"[文件名:%s]\n" "[函数名:%s]\n" "[行号:%d] \n" fmt), __FILE__, __FUNCTION__, __LINE__, ##__VA_ARGS__);

#else//发布模式
#define NSLog(...)
#define KisDebug 0
#endif

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II、 NSLog调试技巧

2.1 Where to find NSLog’s output

NSLog outputs messages to the Apple System Log facility or to the Console app

2.2 Improved logging in Objective-C

• Improved logging in Objective-C

宏	格式说明符	描述
func	%s	当前函数签名
LINE	%d	在源代码文件的当前行号
FILE	%s	源代码文件的完整路径
PRETTY_FUNCTION	%s	print the name of the function being called

表达	格式说明符	描述
NSStringFromSelector(_cmd)	%@	Name of the current selector
NSStringFromClass([self class])	%@	Name of the current object’s class
[[NSString stringWithUTF8String:FILE] lastPathComponent]	%@	Name of the source code file(源代码文件的名称)
[NSThread callStackSymbols]	%@	NSArray of the current stack trace as programmer

• Format specifiers for data types

Type	Format specifier	Considerations
NSInteger	%ld or %lx	Cast the value to long.
NSUInteger	%lu or %lx	Cast the value to unsigned long.
CGFloat	%f or %g	%f works for floats and doubles when formatting; but note the technique described below for scanning.
CFIndex	%ld or %lx	The same as NSInteger.
pointer	%p or %zx	%p adds 0x to the beginning of the output. If you don’t want that, use %zx and no typecast.

2.1 Objective-C’s boxing capability (装箱快速构造数字对象)

The printf function NSLog offers a number of substitution tokens for printing numbers (%d, %ld, %f, %d, for example). As a convenience, you can use Objective-C’s boxing capability to save time and avoid compiler warnings.

• For example

平常也可以使用@ 来快速包装数字类型以对象的形式进行存储和传参

    [discountArray addObject:[[ self class] mj_objectWithKeyValues:@{@"placeholder":QCTLocal(@"please_input_card_num"),@"btnContent":QCTLocal(@"member_see"),@"EnterModelType":@2,@"isEnabled":@1,@"isLast":@1,@"block":block}]];

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2.2 知识补充：装箱和拆箱

• Java包装类(装箱和拆箱)

全部被final修饰，顺便提一下，java.lang.Math,System,String也被final修饰
包装类是使用面向对象的思想把简单的数据类型封装成类。
1.特点
包装类把简单的数据类型包装成类。
注：简单数据类型不是类，使用简单数据类型主要为了提高代码的运行效率
2.装箱和拆箱
把简单数据类型包装成对应的包装类称为boxing(示例：Integer i=1;将1包装成Integer再使用Object引用Integer对象)
把包装类型转换成简单数据类型称为unboxing（示例：Integer i=1，int p=i;//将包装类Integer转化成简单数据类型int）
注：Integer的拆箱方法为 int intValue()，其他的包装类以此类推
1）包装类都重写了toString方法，equals方法，hashCode方法
2）Integer的API:
String toBinaryString(int i); 将int类型的数据以二进制字符串形式返回
int parseInt(String) 将字符串转化成int类型
int parseInt(Stringstr,int i ) 将字符串转化成对应的进制 类型,str为被转换的字符串，i为进制类型（10,8,16）
Integer valueof(String str) 将字符串转换成Integer类型。

see also

• String Format Specifiers

Specifier	Description
%@	Objective-C object, printed as the string returned by descriptionWithLocale: if available, or descriptionotherwise. Also works with CFTypeRef objects, returning the result of the CFCopyDescription function.
%%	'%' character.
%d, %D	Signed 32-bit integer (int).
%u, %U	Unsigned 32-bit integer (unsigned int).
%x	Unsigned 32-bit integer (unsigned int), printed in hexadecimal using the digits 0–9 and lowercase a–f.
%X	Unsigned 32-bit integer (unsigned int), printed in hexadecimal using the digits 0–9 and uppercase A–F.
%o, %O	Unsigned 32-bit integer (unsigned int), printed in octal.
%f	64-bit floating-point number (double).
%e	64-bit floating-point number (double), printed in scientific notation using a lowercase e to introduce the exponent.
%E	64-bit floating-point number (double), printed in scientific notation using an uppercase E to introduce the exponent.
%g	64-bit floating-point number (double), printed in the style of %e if the exponent is less than –4 or greater than or equal to the precision, in the style of %f otherwise.
%G	64-bit floating-point number (double), printed in the style of %E if the exponent is less than –4 or greater than or equal to the precision, in the style of %f otherwise.
%c	8-bit unsigned character (unsigned char).
%C	16-bit UTF-16 code unit (unichar).
%s	Null-terminated array of 8-bit unsigned characters. Because the %s specifier causes the characters to be interpreted in the system default encoding, the results can be variable, especially with right-to-left languages. For example, with RTL, %s inserts direction markers when the characters are not strongly directional. For this reason, it’s best to avoid %s and specify encodings explicitly.
%S	Null-terminated array of 16-bit UTF-16 code units.
%p	Void pointer (void *), printed in hexadecimal with the digits 0–9 and lowercase a–f, with a leading 0x.
%a	64-bit floating-point number (double), printed in scientific notation with a leading 0x and one hexadecimal digit before the decimal point using a lowercase p to introduce the exponent.
%A	64-bit floating-point number (double), printed in scientific notation with a leading 0X and one hexadecimal digit before the decimal point using a uppercase P to introduce the exponent.
%F	64-bit floating-point number (double), printed in decimal notation.

• Format specifiers for data types

Type	Format specifier	Considerations
NSInteger	%ld or %lx	Cast the value to long.
NSUInteger	%lu or %lx	Cast the value to unsigned long.
CGFloat	%f or %g	%f works for floats and doubles when formatting; but note the technique described below for scanning.
CFIndex	%ld or %lx	The same as NSInteger.
pointer	%p or %zx	%p adds 0x to the beginning of the output. If you don’t want that, use %zx and no typecast.

• Basic debugging

Log facility 和level的关系

NSLog outputs messages to the Apple System Log facility or to the Console app

• facility：是系统对某种类型事件的定义。

LOG_AUTH
LOG_AUTHPRIV 安全认证
LOG_CRON clock daemon (cron and at) 计划任务事件
LOG_DAEMON 后台进程
LOG_FTP ftp daemon
LOG_KERN kernel messages
LOG_LOCAL0 through LOG_LOCAL7 用户自定义设备
LOG_LPR printer subsystem
LOG_MAIL 邮件系统mail subsystem
LOG_NEWS news subsystem
LOG_SYSLOG syslogd自身产生的日志
LOG_USER (default)

• level :指遇到何种情况才记录日志

从下到上，级别从低到高，记录的信息越来越少

LOG_EMERG 紧急，致命，服务无法继续运行，如配置文件丢失
LOG_ALERT 报警，需要立即处理，如磁盘空使用95%
LOG_CRIT 致命行为
LOG_ERR 错误行为
LOG_WARNING 警告信息
LOG_NOTICE 普通，重要的标准信息
LOG_INFO 标准信息
LOG_DEBUG 调试信息，排错所需，一般不建议使用

常见的日志文件

tail /var/log/messages //系统主日志文件
tail -20 /var/log/messages
tail -f /var/log/messages //动态查看日志文件的尾部
tailf /var/log/secure //认证、安全
tail /var/log/maillog //跟邮件postfix相关
tail /var/log/cron //crond、at进程产生的日志
tail /var/log/dmesg //和系统启动相关
tail /var/log/audit/audit.log //系统审计日志
tail /var/log/yum.log //yum
tail /var/log/mysqld.log //MySQL
tail /var/log/xferlog //和访问FTP服务器相关
w //当前登录的用户 /var/log/wtmp
last //最近登录的用户 /var/log/btmp
lastlog //所有用户的登录情况 /var/log/lastlog

配置【生成/存储日志】策略: vim /etc/rsyslog.conf

由设备+级别+存放位置组成

FACILITY+LEVEL+FILE组成:
authpriv.* /var/log/secure（SSH信息）
mail.* -/var/log/maillog（发邮件）
cron.* /var/log/cron（创建任务）
authpriv.* * <代表所有终端>
authpriv. @192.168.10.230 
authpriv.* @@192.168.10.230 

配置IP

• /etc/sysconfig/network-scripts/ifcfg-enp2s0中各个参数的意义

vim /etc/sysconfig/network-scripts/ifcfg-enp2s0
NAME=“enp2s0”
DEVICE=“enp2s0”
ONBOOT=yes //是否启用该设备
BOOTPROTO=none //手动(none/static)还是自动(dhcp)
IPADDR=172.16.120.246 //地址
PREFIX=24 //掩码
IPADDR1=192.168.200.246 //额外地址
PREFIX1=24 //额外掩码，注意编号
GATEWAY=172.16.120.254 //网关
DNS1=8.8.8.8 //DNS
DNS2=114.114.114.114 //DNS2

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