[Ios] hex conversion algorithm to ASC

How to convert a hexadecimal asc example: 0x31 ---> 1
I wanted to write a method but purely with string manipulation too much trouble, I would like to know by post under objective-c there is no built-in functions can be used to improve the effectiveness, I hope ios heroes help Xianxie !
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Top about themselves ....
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landlord references replies:

how to convert a hexadecimal asc example: 0x31 ---> 1
I wanted to write a method but purely with string manipulation too much trouble, I would like to know by post under objective-c there is no built-in functions can be used to improve the effectiveness, I hope ios heroes help Xianxie !

Should be 0x31 ---- "'1 'this, right?
If it is 0x31 --- "1, subtract 0x30 not on the line?
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reference to the second floor of the reply:

landlord references replies:
How to convert a hexadecimal asc example: 0x31 ---> 1
I wanted to write a method but purely with string manipulation too much trouble, I would like to know by post under objective-c there is no built-in functions can be used to improve the effectiveness, I hope ios heroes help Xianxie !

Should be 0x31 ---- "'1 'this, right?
If it is 0x31 --- "1, subtract 0x30 not on the line?

This you misunderstood, 0x31 -> "1" I just give an example fills a hex turn after some asc code becomes not visible characters
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Character '1 'in ASCII encoding value is 0x31.
That is, here, for example, the hexadecimal representation of the character itself is 0x31 '1 'ASCII encoded values.
char c1 = 0x31;

ASCII encoding, UTF-8 character encoding, etc.,
0xXXX, this metric.

Do not understand what you ask. "Hex convert ASC algorithm," what is meant.

Is not ask to convert a hexadecimal value between characters?
char c1 = 0x31; This conversion count?

"Some turn asc after a hexadecimal code will become non-visible character"
Because the ASCII character itself is invisible characters,,





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I actually want to seek help of a string into BCD