CODEWITHSUNDEEP
ioscocoa-touchnsstring
Ser Pounce
Ser Pounce

Reputation: 14553

Way to detect character that takes up more than one index spot in an NSString?

I'm wondering, is there a way to detect a character that takes up more than 1 index spot in an NSString? (like an emoji). I'm trying to implement a custom text view and when the user pushes delete, I need to know if I should delete only the previous one index spot or more.

Upvotes: 1

Views: 94

Answers (2)

codester
codester

Reputation: 37189

Actually NSString use UTF-16.So it is quite difficult to work with characters which takes two UTF-16 charater(unichar) or more.But you can do with rangeOfComposedCharacterSequenceAtIndexto get range and than delete.

First find the last character index from string

NSUInteger lastCharIndex = [str length] - 1;

Than get the range of last character

NSRange lastCharRange = [str rangeOfComposedCharacterSequenceAtIndex: lastCharIndex];

Than delete with range from character (If it is of two UTF-16 than it deletes UTF-16)

deletedLastCharString = [str substringToIndex: lastCharRange.location];

You can use this method with any type of characters which takes any number of unichar

Upvotes: 3

Majster
Majster

Reputation: 3701

For one you could transform the string to a sequence of characters using [myString UTF8String] and you can then check if the character has its first bit set to one or zero. If its one then this is a UTF8 character and you can then check how many bytes are there to this character. Details about UTF8 can be found on Wikipedia - UTF8. Here is a simple example:

NSString *string = @"ČTest";
const char *str = [string UTF8String];
NSMutableString *ASCIIStr = [NSMutableString string];

for (int i = 0; i < strlen(str); ++i)
    if (!(str[i] & 128))
        [ASCIIStr appendFormat:@"%c", str[i]];

NSLog(@"%@", ASCIIStr); //Should contain only ASCII characters

Upvotes: 1

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