Creating NSFormatters(Chapter 26 of Cocoa Programming for Mac OS X)

  1 #import "ColorFormatter.h"
  2 
  3 @interface ColorFormatter()
  4 
  5 - (NSString *)firstColorKeyForPartialString:(NSString *)string;
  6 
  7 @end
  8 
  9 @implementation ColorFormatter
 10 
 11 - (id)init
 12 {
 13     [super init];
 14     colorList = [[NSColorList colorListNamed:@"Apple"] retain];
 15     return self;
 16 }
 17 
 18 - (void)dealloc
 19 {
 20     [colorList release];
 21     [super dealloc];
 22 }
 23 
 24 - (NSString *)firstColorKeyForPartialString:(NSString *)string
 25 {
 26     if([string length] == 0)
 27     {
 28         return nil;
 29     }
 30     
 31     for(NSString *key in [colorList allKeys])
 32     {
 33         NSRange whereFound = [key rangeOfString:string options:NSCaseInsensitiveSearch];
 34         if ((whereFound.location == 0) && (whereFound.length > 0)) 
 35         {
 36             return key;
 37         }
 38     }
 39     
 40     return nil;
 41 }
 42 
 43 - (NSString *)stringForObjectValue:(id)obj
 44 {
 45     if(![obj isKindOfClass:[NSColor class]])
 46     {
 47         return nil;
 48     }
 49     
 50     NSColor *color;
 51     color = [obj colorUsingColorSpaceName:NSCalibratedRGBColorSpace];
 52     
 53     CGFloat red, green, blue;
 54     [color getRed:&red green:&green blue:&blue alpha:NULL];
 55     
 56     float minDistance = 3.0;
 57     NSString *closestKey = nil;
 58     for(NSString *key in [colorList allKeys])
 59     {
 60         NSColor *c = [colorList colorWithKey:key];
 61         CGFloat r, g, b;
 62         [c getRed:&r green:&g blue:&b alpha:NULL];
 63         
 64         float dist;
 65         dist = pow(red-r, 2) + pow(green-g, 2) + pow(blue-b, 2);
 66         if(dist < minDistance)
 67         {
 68             minDistance = dist;
 69             closestKey = key;
 70         }
 71     }
 72     
 73     return closestKey;
 74 }
 75 
 76 - (BOOL)getObjectValue:(id *)obj forString:(NSString *)string errorDescription:(NSString **)error
 77 {
 78     NSString *matchingKey = [self firstColorKeyForPartialString:string];
 79     if(matchingKey)
 80     {
 81         *obj = [colorList colorWithKey:matchingKey];
 82         return YES;
 83     }
 84     else 
 85     {
 86         if(error != NULL)
 87         {
 88             *error = [NSString stringWithFormat:@"'%@' is not a color", string];
 89         }
 90         return NO;
 91     }
 92 
 93 }
 94 
 95 /*
 96 - (BOOL)isPartialStringValid:(NSString *)partialString newEditingString:(NSString **)newString errorDescription:(NSString **)error
 97 {
 98     if([partialString length] == 0)
 99     {
100         return YES;
101     }
102     
103     NSString *match = [self firstColorKeyForPartialString:partialString];
104     if(match)
105     {
106         return YES;
107     }
108     else 
109     {
110         if (error) 
111         {
112             *error = @"No such color";
113         }
114         return NO;
115     }
116 }
117 */
118 
119 - (BOOL)isPartialStringValid:(NSString **)partial proposedSelectedRange:(NSRange *)selPtr originalString:(NSString *)origString originalSelectedRange:(NSRange)origSel errorDescription:(NSString **)error
120 {
121     if([*partial length] == 0)
122     {
123         return YES;
124     }
125     
126     NSString *match = [self firstColorKeyForPartialString:*partial];
127     if(!match)
128     {
129         return NO;
130     }
131     
132     if (origSel.location == selPtr->location) 
133     {
134         return YES;
135     }
136     
137     if([match length] != [*partial length])
138     {
139         selPtr->location = [*partial length];
140         selPtr->length = [match length] - selPtr->location;
141         *partial = match;
142         return NO;
143     }
144     
145     return YES;
146 }
147 
148 - (NSAttributedString *)attributedStringForObjectValue:(id)obj withDefaultAttributes:(NSDictionary *)attrs
149 {
150     NSMutableDictionary *md = [attrs mutableCopy];
151     NSString *match = [self stringForObjectValue:obj];
152     if(match)
153     {
154         [md setObject:obj forKey:NSForegroundColorAttributeName];
155     }
156     else 
157     {
158         match = @"";
159     }
160     NSAttributedString *atString;
161     atString = [[NSAttributedString alloc] initWithString:match attributes:md];
162     [md release];
163     [atString autorelease];
164     return atString;
165 }
166 
167 @end