NSString stringByPaddingToLength example ios

stringByPaddingToLength: withString: startingAtIndex:

Returns a new string formed from the receiver by either removing characters from the end, or by appending as many occurrences as necessary of a given pad string.

- (NSString *)stringByPaddingToLength:(NSUInteger)newLengthwithString:(NSString *)padString startingAtIndex:(NSUInteger)padIndex

Parameters

newLength

The new length for the receiver.

padString

The string with which to extend the receiver.

padIndex

The index in padString from which to start padding.

Return Value of [NSString stringByPaddingToLength]

A new string formed from the receiver by either removing characters from the end, or by appending as many occurrences of padString as necessary.

Discussion of [NSString stringByPaddingToLength]

Here are some examples of usage:

[@"abc" stringByPaddingToLength: 9 withString: @"." startingAtIndex:0];

// Results in "abc......"

[@"abc" stringByPaddingToLength: 2 withString: @"." startingAtIndex:0];

// Results in "ab"

[@"abc" stringByPaddingToLength: 9 withString: @". " startingAtIndex:1];

// Results in "abc . . ."

// Notice that the first character in the padding is " "

Example of [NSString stringByPaddingToLength]

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;
}

Example of [NSString stringByPaddingToLength]

- (NSString *)formattedStringWithStrings:(NSArray *)strings {

    NSString *str1 = [[strings objectAtIndex:0] stringByPaddingToLength:3 withString:@" " startingAtIndex:0];
    NSString *str2 = [[strings objectAtIndex:1] stringByPaddingToLength:20 withString:@" " startingAtIndex:0];
    NSString *str3 = [[strings objectAtIndex:2] stringByPaddingToLength:3 withString:@" " startingAtIndex:0];
    NSString *str4 = [[strings objectAtIndex:3] stringByPaddingToLength:10 withString:@" " startingAtIndex:0];
    NSString *str5 = [[strings objectAtIndex:4] stringByPaddingToLength:15 withString:@" " startingAtIndex:0];
    return [NSString stringWithFormat:@"%@%@%@%@%@", str1, str2, str3, str4, str5]; 
}

Example of [NSString stringByPaddingToLength]

@implementation NSString (LeftPadding)

- (NSString *) stringByPaddingTheLeftToLength:(NSUInteger) newLength withString:(NSString *) padString startingAtIndex:(NSUInteger) padIndex
{
    if ([self length] <= newLength)
        return [[@"" stringByPaddingToLength:newLength - [self length] withString:padString startingAtIndex:padIndex] stringByAppendingString:self];
    else
        return [[self copy] autorelease];
}

@end