ios NSLog常见使用

时间:2021-07-23 10:50:38

NSLog常见输出格式

Table 1  Format specifiers supported by the NSString formatting methods and CFString formatting functions

Specifier

Description

%@

Objective-C object, printed as the string returned by descriptionWithLocale: if available, or description otherwise. Also works withCFTypeRef objects, returning the result of the CFCopyDescription function.

%%

'%' character

%d, %D,%i

Signed 32-bit integer (int)

%u, %U

Unsigned 32-bit integer (unsigned int)

%hi

Signed 16-bit integer (short)

%hu

Unsigned 16-bit integer (unsigned short)

%qi

Signed 64-bit integer (long long)

%qu

Unsigned 64-bit integer (unsigned long long)

%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

%qx

Unsigned 64-bit integer (unsigned long long), printed in hexadecimal using the digits 0–9 and lowercase a–f

%qX

Unsigned 64-bit integer (unsigned long long), 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), printed by NSLog() as an ASCII character, or, if not an ASCII character, in the octal format \\ddd or the Unicode hexadecimal format \\udddd, where d is a digit

%C

16-bit Unicode character (unichar), printed by NSLog() as an ASCII character, or, if not an ASCII character, in the octal format \\ddd or the Unicode hexadecimal format \\udddd, where d is a digit

%s

Null-terminated array of 8-bit unsigned characters. %s interprets its input in the system encoding rather than, for example, UTF-8.

%S

Null-terminated array of 16-bit Unicode characters

%p

Void pointer (void *), printed in hexadecimal with the digits 0–9 and lowercase a–f, with a leading 0x

%L

Length modifier specifying that a following a, A, e, E, f, F, g, or G conversion specifier applies to a long double argument

%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

%z

Length modifier specifying that a following d, i, o, u, x, or X conversion specifier applies to a size_t or the corresponding signed integer type argument

%t

Length modifier specifying that a following d, i, o, u, x, or X conversion specifier applies to a ptrdiff_t or the corresponding unsigned integer type argument

%j

Length modifier specifying that a following d, i, o, u, x, or X conversion specifier applies to a intmax_t or uintmax_t argument

下面可能也是比较常见的

  NSLog(@"rect = %@",NSStringFromCGRect(self.view.frame));

NSLog(@"size = %@",NSStringFromCGSize(self.view.frame.size));

NSLog(@"point = %@",NSStringFromCGPoint(self.view.frame.origin));

NSLog 与 printf 的区别

1.NSLog会自己加上换行符

2.NSLog在Debug下会写到system.log中

3.NSLog会自动加上时间和进程信息.

4.NSLog支持%@去打印一个对象类型,当使用%@时,它会给对象发送消息description,所以如果你组合了一个新的类,你可以通过给自己重载description来实现打印DEBUG