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eiffelqiu/NSString-truncateToSize.h

Created May 24, 2011 06:57
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NSString truncation to given size
Raw
NSString-truncateToSize.h
//
// NSString-truncateToSize
// Fast Fonts
//
// Created by Stuart Shelton on 28/03/2010.
// Copyright 2010 Stuart Shelton.
//
// NSString truncate function for Objective C / iPhone SDK by
// Stuart Shelton is licensed under a Creative Commons Attribution 3.0
// Unported License (CC BY 3.0)
//
// http://creativecommons.org/licenses/by/3.0/
//
#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>
@interface NSString (truncateToSize)
- (NSString *)truncateToSize: (CGSize)size withFont: (UIFont *)font lineBreakMode: (UILineBreakMode)lineBreakMode;
- (NSString *)truncateToSize: (CGSize)size withFont: (UIFont *)font lineBreakMode: (UILineBreakMode)lineBreakMode withAnchor: (NSString *)anchor;
- (NSString *)truncateToSize: (CGSize)size withFont: (UIFont *)font lineBreakMode: (UILineBreakMode)lineBreakMode withStartingAnchor: (NSString *)startingAnchor withEndingAnchor: (NSString *)endingAnchor;
@end
Raw
NSString-truncateToSize.m
//
// NSString-truncateToSize
// Fast Fonts
//
// Created by Stuart Shelton on 28/03/2010.
// Copyright 2010 Stuart Shelton.
//
// NSString truncate function for Objective C / iPhone SDK by
// Stuart Shelton is licensed under a Creative Commons Attribution 3.0
// Unported License (CC BY 3.0)
//
// http://creativecommons.org/licenses/by/3.0/
//
#import "NSString-truncateToSize.h"
@implementation NSString (truncateToSize)
- (NSString *)truncateToSize: (CGSize)size withFont: (UIFont *)font lineBreakMode: (UILineBreakMode)lineBreakMode {
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode withStartingAnchor: nil withEndingAnchor: nil];
} /* (NSString *)truncateToSize: withFont: lineBreakMode: */
- (NSString *)truncateToSize: (CGSize)size withFont: (UIFont *)font lineBreakMode: (UILineBreakMode)lineBreakMode withAnchor: (NSString *)anchor {
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode withStartingAnchor: anchor withEndingAnchor: anchor];
} /* (NSString *)truncateToSize: withFont: lineBreakMode: withAnchor: */
- (NSString *)truncateToSize: (CGSize)size withFont: (UIFont *)font lineBreakMode: (UILineBreakMode)lineBreakMode withStartingAnchor: (NSString *)startingAnchor withEndingAnchor: (NSString *)endingAnchor {
if( !( lineBreakMode & ( UILineBreakModeHeadTruncation | UILineBreakModeMiddleTruncation | UILineBreakModeTailTruncation ) ) )
return self;
if( [self sizeWithFont: font].width <= size.width )
return self;
NSString *ellipsis = @"…";
// Note that this code will find the first occurrence of any given anchor,
// so be careful when choosing anchor characters/strings...
NSInteger start;
if( startingAnchor ) {
start = [self rangeOfString: startingAnchor options: NSLiteralSearch].location;
if( NSNotFound == start ) {
if( [startingAnchor isEqualToString: endingAnchor] )
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode];
else
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode withAnchor: endingAnchor];
}
} else {
start = 0;
}
NSUInteger end;
if( endingAnchor ) {
end = [self rangeOfString: endingAnchor options: NSLiteralSearch range: NSMakeRange( start + 1, [self length] - start - 1 )].location;
if( NSNotFound == end ) {
if( [startingAnchor isEqualToString: endingAnchor] )
// Shouldn't ever occur, since filtered out in block above...
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode];
else
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode withAnchor: startingAnchor];
}
} else {
end = [self length];
}
NSUInteger targetLength = end - start;
if( [[self substringWithRange: NSMakeRange( start, targetLength )] sizeWithFont: font].width < [ellipsis sizeWithFont: font].width )
if( startingAnchor || endingAnchor )
return [self truncateToSize: size withFont: font lineBreakMode: lineBreakMode];
else
return self;
NSMutableString *truncatedString = [[NSMutableString alloc] initWithString: self];
switch( lineBreakMode ) {
case UILineBreakModeHeadTruncation:
// Avoid anchor...
if( startingAnchor )
start++;
while( targetLength > [ellipsis length] + 1 && [truncatedString sizeWithFont: font].width > size.width) {
// Replace our ellipsis and one additional following character with our ellipsis
NSRange range = NSMakeRange( start, [ellipsis length] + 1 );
[truncatedString replaceCharactersInRange: range withString: ellipsis];
targetLength--;
}
break;
case UILineBreakModeMiddleTruncation:
{
NSUInteger leftEnd = start + ( targetLength / 2 );
NSUInteger rightStart = leftEnd + 1;
if( leftEnd + 1 <= rightStart - 1 )
break;
// leftPre and rightPost consist of any characters before and beyond
// any specified anchor(s).
// left and right are the two halves of the string to be truncated - although
// the initial split is still performed based upon the length of the
// (sub)string to be truncated, so we could still make a bad initial split given
// a short string with predominantly narrow characters on one side and wide
// characters on the other.
NSString *leftPre = @"";
if( startingAnchor )
leftPre = [truncatedString substringWithRange: NSMakeRange( 0, start + 1 )];
NSMutableString *left = [NSMutableString stringWithString: [truncatedString substringWithRange: NSMakeRange( ( startingAnchor ? start + 1 : start ), leftEnd - start )]];
NSMutableString *right = [NSMutableString stringWithString: [truncatedString substringWithRange: NSMakeRange( rightStart, end - rightStart )]];
NSString *rightPost = @"";
if( endingAnchor )
rightPost = [truncatedString substringWithRange: NSMakeRange( end, [truncatedString length] - end )];
/* NSLog( @"pre '%@', left '%@', right '%@', post '%@'", leftPre, left, right, rightPost ); */
// Reassemble substrings
[truncatedString setString: [NSString stringWithFormat: @"%@%@%@%@%@", leftPre, left, ellipsis, right, rightPost]];
while( leftEnd > start + 1 && rightStart < end + 1 && [truncatedString sizeWithFont: font].width > size.width) {
CGFloat leftLength = [left sizeWithFont: font].width;
CGFloat rightLength = [right sizeWithFont: font].width;
// Shorten string of longest width
if( leftLength > rightLength ) {
[left deleteCharactersInRange: NSMakeRange( [left length] - 1, 1 )];
leftEnd--;
} else { /* ( leftLength <= rightLength ) */
[right deleteCharactersInRange: NSMakeRange( 0, 1 )];
rightStart++;
}
/* NSLog( @"pre '%@', left '%@', right'%@', post '%@'", leftPre, left, right, rightPost ); */
[truncatedString setString: [NSString stringWithFormat: @"%@%@%@%@%@", leftPre, left, ellipsis, right, rightPost]];
}
}
break;
case UILineBreakModeTailTruncation:
while( targetLength > [ellipsis length] + 1 && [truncatedString sizeWithFont: font].width > size.width) {
// Remove last character
NSRange range = NSMakeRange( --end, 1);
[truncatedString deleteCharactersInRange: range];
// Replace original last-but-one (now last) character with our ellipsis...
range = NSMakeRange( end - [ellipsis length], [ellipsis length] );
[truncatedString replaceCharactersInRange: range withString: ellipsis];
targetLength--;
}
break;
}
NSString *result = [NSString stringWithString: truncatedString];
[truncatedString release];
return result;
} /* (NSString *)truncateToSize: withFont: lineBreakMode: withStartingAnchor: withEndingAnchor: */
@end
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