Added Documentation

MathPad/NSIndexPath+MPAdditions.m

@@ -8,23 +8,29 @@
 
 #import "NSIndexPath+MPAdditions.h"
 
+
+
 @implementation NSIndexPath (MPAdditions)
 
+
 - (NSUInteger)firstIndex
 {
     return [self indexAtPosition:0];
 }
 
+
 - (NSUInteger)lastIndex
 {
     return [self indexAtPosition:self.length-1];
 }
 
+
 - (NSIndexPath *)indexPathByReplacingLastIndexWithIndex:(NSUInteger)index
 {
     return [[self indexPathByRemovingLastIndex] indexPathByAddingIndex:index];
 }
 
+
 - (NSIndexPath *)indexPathByRemovingFirstIndex
 {
     if (self.length <= 1) {
@@ -39,6 +45,7 @@
     return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length-1];
 }
 
+
 - (NSIndexPath *)indexPathByPreceedingIndex:(NSUInteger)index
 {
     NSUInteger newIndexes[self.length+1];
@@ -49,8 +56,12 @@
     return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length+1];
 }
 
+
 - (NSIndexPath *)indexPathByIncrementingLastIndex
 {
+    if (self.length < 1) {
+        return [[NSIndexPath alloc] init];
+    }
     NSUInteger lastIndex = [self lastIndex];
     lastIndex++;
     return [[self indexPathByRemovingLastIndex] indexPathByAddingIndex:lastIndex];
@@ -58,29 +69,35 @@
 
 - (NSIndexPath *)indexPathByDecrementingLastIndex
 {
+    if (self.length < 1) {
+        return [[NSIndexPath alloc] init];
+    }
     NSUInteger lastIndex = [self lastIndex];
     lastIndex--;
     return [[self indexPathByRemovingLastIndex] indexPathByAddingIndex:lastIndex];
 }
 
-- (NSIndexPath *)indexPathByRemovingIndexesFrom:(NSUInteger)length
+
+- (NSIndexPath *)indexPathByRemovingIndexesFrom:(NSUInteger)from
 {
     NSIndexPath *indexPath = [[NSIndexPath alloc] init];
-    for (NSUInteger position = 0; position < length; position++) {
+    for (NSUInteger position = 0; position < MIN(from, self.length); position++) {
         indexPath = [indexPath indexPathByAddingIndex:[self indexAtPosition:position]];
     }
     return indexPath;
 }
 
-- (NSIndexPath *)indexPathByRemovingIndexesTo:(NSUInteger)length
+
+- (NSIndexPath *)indexPathByRemovingIndexesTo:(NSUInteger)to
 {
     NSIndexPath *indexPath = [[NSIndexPath alloc] init];
-    for (NSUInteger position = length; position < self.length; position++) {
+    for (NSUInteger position = to; position < self.length; position++) {
         indexPath = [indexPath indexPathByAddingIndex:[self indexAtPosition:position]];
     }
     return indexPath;
 }
 
+
 - (NSIndexPath *)commonIndexPathWith:(NSIndexPath *)indexPath
 {
     NSIndexPath *commonPath = [[NSIndexPath alloc] init];