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ios NSLog常见使用
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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