How to pad NSString with spaces?

问题

For example, I need the NSString have at least 8 chars....instead of using a loop to add the left pad spaces on this, is there anyway to do it?

Examples:

Input:    |Output:
Hello     |   Hello
Bye       |     Bye
Very Long |Very Long
abc       |     abc

回答1:

Here is an example of how you can do it:

int main (int argc, const char * argv[]) {
    NSString *str = @"Hello";
    int add = 8-[str length];
    if (add > 0) {
        NSString *pad = [[NSString string] stringByPaddingToLength:add withString:@" " startingAtIndex:0];
        str = [pad stringByAppendingString:str];
    }
    NSLog(@"'%@'", str);
    return 0;
}

回答2:

I just do something like this:

    NSLog(@"%*c%@", 14 - theString.length, ' ', theString);

Moreover, 14is the width that you want.

回答3:

You can use C language printf formatting with -[NSMutableString appendFormat:] and all other NSString "format" methods. It doesn't respect NSString (do formatting on %@), so you need to convert them to ASCII.

String Padding in C

- (NSString *)sample {
    NSArray<NSString *> *input = @[@"Hello", @"Bye", @"Very Long", @"abc"];
    NSMutableString *output = [[NSMutableString alloc] init];
    for (NSString *string in input) {
        [output appendFormat:@"%8s\n", string.UTF8String];
    }
    return output;
}

/*
Return value:
   Hello
     Bye
Very Long
     abc
*/

回答4:

if you need the same answer in a method, I had to create one for use in my projects. original code by dashblinkenlight

- (NSString *) LeftPadString: (NSString*) originalString LengthAfterPadding: (int)len  paddingCharacter: (char) pad
{
int add = (int) (len - originalString.length);

NSString* paddingCharString = [NSString stringWithFormat:@"%c" , pad];

if (add > 0)
{
    NSString *pad = [[NSString string] stringByPaddingToLength:add withString: paddingCharString startingAtIndex:0];
    return [pad stringByAppendingString:originalString];
}
else
    return originalString;
}

来源：https://stackoverflow.com/questions/8651210/how-to-pad-nsstring-with-spaces

标签

objective-c

nsstring

padding