Factor date formatting into reusable convenience functions

Code/ObjectMapping/RKMappingOperation.m

@@ -76,6 +76,9 @@ extern NSString * const RKObjectMappingNestingAttributeKeyName;
 @property (nonatomic, strong) RKObjectMapping *objectMapping; // The concrete mapping
 @end
 
+// Defined in RKObjectMapping.h
+NSDate *RKDateFromStringWithFormatters(NSString *dateString, NSArray *formatters);
+
 @implementation RKMappingOperation
 
 - (id)initWithSourceObject:(id)sourceObject destinationObject:(id)destinationObject mapping:(RKMapping *)objectOrDynamicMapping
@@ -98,35 +101,7 @@ extern NSString * const RKObjectMappingNestingAttributeKeyName;
 - (NSDate *)parseDateFromString:(NSString *)string
 {
     RKLogTrace(@"Transforming string value '%@' to NSDate...", string);
-
-    NSDate *date = nil;
-
-    if (![string isEqualToString:@""]) {
-        for (NSFormatter *dateFormatter in self.objectMapping.dateFormatters) {
-            BOOL success;
-            @synchronized(dateFormatter) {
-                if ([dateFormatter isKindOfClass:[NSDateFormatter class]]) {
-                    RKLogTrace(@"Attempting to parse string '%@' with format string '%@' and time zone '%@'", string, [(NSDateFormatter *)dateFormatter dateFormat], [(NSDateFormatter *)dateFormatter timeZone]);
-                }
-                NSString *errorDescription = nil;
-                success = [dateFormatter getObjectValue:&date forString:string errorDescription:&errorDescription];
-            }
-
-            if (success && date) {
-                if ([dateFormatter isKindOfClass:[NSDateFormatter class]]) {
-                    RKLogTrace(@"Successfully parsed string '%@' with format string '%@' and time zone '%@' and turned into date '%@'",
-                                string, [(NSDateFormatter *)dateFormatter dateFormat], [(NSDateFormatter *)dateFormatter timeZone], date);
-                } else if ([dateFormatter isKindOfClass:[NSNumberFormatter class]]) {
-                    NSNumber *formattedNumber = (NSNumber *)date;
-                    date = [NSDate dateWithTimeIntervalSince1970:[formattedNumber doubleValue]];
-                }
-
-                break;
-            }
-        }
-    }
-
-    return date;
+    return RKDateFromStringWithFormatters(string, self.objectMapping.dateFormatters);
 }
 
 - (id)transformValue:(id)value atKeyPath:(NSString *)keyPath toType:(Class)destinationType

Code/ObjectMapping/RKObjectMapping.h

@@ -346,3 +346,29 @@
 + (void)setPreferredDateFormatter:(NSFormatter *)dateFormatter;
 
 @end
+
+///----------------
+/// @name Functions
+///----------------
+
+/**
+ Returns an date representation of a given string value by attempting to parse the string with all default date formatters in turn.
+
+ @param dateString A string object encoding a date value.
+ @return An `NSDate` object parsed from the given string, or `nil` if the string was found to be unparsable by all default date formatters.
+ @see [RKObjectMapping defaultDateFormatters]
+ */
+NSDate *RKDateFromString(NSString *dateString);
+
+/**
+ Returns a string representation of a given date formatted with the preferred date formatter.
+
+ This is a convenience function that is equivalent to the following example code:
+
+    NSString *string = [[RKObjectMapping preferredDateFormatter] stringForObjectValue:date]
+
+ @param date The date object to be formatted.
+ @return An `NSString` object representation of the given date formatted by the preferred date formatter.
+ @see [RKObjectMapping preferredDateFormatter]
+ */
+NSString *RKStringFromDate(NSDate *date);

Code/ObjectMapping/RKObjectMapping.m

@@ -30,6 +30,9 @@
 NSString * const RKObjectMappingNestingAttributeKeyName = @"<RK_NESTING_ATTRIBUTE>";
 static NSUInteger RKObjectMappingMaximumInverseMappingRecursionDepth = 100;
 
+// Private declaration
+NSDate *RKDateFromStringWithFormatters(NSString *dateString, NSArray *formatters);
+
 @interface RKObjectMapping ()
 @property (nonatomic, weak, readwrite) Class objectClass;
 @property (nonatomic, strong) NSMutableArray *mutablePropertyMappings;
@@ -404,3 +407,44 @@ static NSDateFormatter *preferredDateFormatter = nil;
 }
 
 @end
+
+#pragma mark - Functions
+
+NSDate *RKDateFromStringWithFormatters(NSString *dateString, NSArray *formatters)
+{
+    NSDate *date = nil;
+    for (NSFormatter *dateFormatter in formatters) {
+        BOOL success;
+        @synchronized(dateFormatter) {
+            if ([dateFormatter isKindOfClass:[NSDateFormatter class]]) {
+                RKLogTrace(@"Attempting to parse string '%@' with format string '%@' and time zone '%@'", dateString, [(NSDateFormatter *)dateFormatter dateFormat], [(NSDateFormatter *)dateFormatter timeZone]);
+            }
+            NSString *errorDescription = nil;
+            success = [dateFormatter getObjectValue:&date forString:dateString errorDescription:&errorDescription];
+        }
+
+        if (success && date) {
+            if ([dateFormatter isKindOfClass:[NSDateFormatter class]]) {
+                RKLogTrace(@"Successfully parsed string '%@' with format string '%@' and time zone '%@' and turned into date '%@'",
+                           dateString, [(NSDateFormatter *)dateFormatter dateFormat], [(NSDateFormatter *)dateFormatter timeZone], date);
+            } else if ([dateFormatter isKindOfClass:[NSNumberFormatter class]]) {
+                NSNumber *formattedNumber = (NSNumber *)date;
+                date = [NSDate dateWithTimeIntervalSince1970:[formattedNumber doubleValue]];
+            }
+
+            break;
+        }
+    }
+
+    return date;
+}
+
+NSDate *RKDateFromString(NSString *dateString)
+{
+    return RKDateFromStringWithFormatters(dateString, [RKObjectMapping defaultDateFormatters]);
+}
+
+NSString *RKStringFromDate(NSDate *date)
+{
+    return [[RKObjectMapping preferredDateFormatter] stringForObjectValue:date];
+}