Refactoring and fixing a bug around nib-instantiated views.

Author: cbowns

MPTextView.m

@@ -7,16 +7,22 @@
 
 #import "MPTextView.h"
 
-// Manually-selected label offset to align placeholder label with real text.
+// Manually-selected label offsets to align placeholder label with text entry.
 static CGFloat const kLabelLeftOffset = 8.f;
+static CGFloat const kLabelTopOffset = 0.f;
+
+// When instantiated from IB, the text view has an 8 point top offset:
+static CGFloat const kLabelTopOffsetFromIB = 8.f;
+// On retina iPhones and iPads, the label is offset by 0.5 points:
 static CGFloat const kLabelTopOffsetRetina = 0.5f;
 
 @interface MPTextView ()
 
 @property (nonatomic, strong) UILabel *placeholderLabel;
 
-// Calculate and save the label's left and top offset.
-@property (nonatomic, assign) CGSize labelOffset;
+// The top offset differs when the view is instantiated from IB or programmatically.
+// Use this to track the instantiation route and offset the label accordingly.
+@property (nonatomic, assign) CGFloat topLabelOffset;
 
 // Handle text changed event so we can update the placeholder appropriately
 - (void)textChanged:(NSNotification *)note;
@@ -31,23 +37,26 @@ @implementation MPTextView
 - (id)initWithCoder:(NSCoder *)aDecoder {
     self = [super initWithCoder:aDecoder];
     if (self) {
+        // Account for IB offset:
+        _topLabelOffset = kLabelTopOffsetFromIB;
         [self finishInitialization];
     }
     return self;
 }
 
-
 - (id)initWithFrame:(CGRect)frame {
     self = [super initWithFrame:frame];
     if (self) {
+        _topLabelOffset = kLabelTopOffset;
         [self finishInitialization];
     }
     return self;
 }
 
-
 // Private method for finishing initialization.
-// Rather than muck with designated initializers, let's do it the easy way.
+// Since this class isn't documented for subclassing,
+// I don't feel comfortable changing the initializer chain.
+// Let's do it this way rather than overriding UIView's designated initializer.
 - (void)finishInitialization {
     // Sign up for notifications for text changes:
     [[NSNotificationCenter defaultCenter] addObserver:self
@@ -56,44 +65,48 @@ - (void)finishInitialization {
                                                object:self];
 
     CGFloat labelLeftOffset = kLabelLeftOffset;
-    CGFloat labelTopOffset = 0.f;
+    // Use our calculated label offset from initWith…:
+    CGFloat labelTopOffset = self.topLabelOffset;
 
     // On retina iPhones and iPads, the label is offset by 0.5 points.
     if ([[UIScreen mainScreen] scale] == 2.0) {
-        labelTopOffset = kLabelTopOffsetRetina;
+        labelTopOffset += kLabelTopOffsetRetina;
     }
-    self.labelOffset = CGSizeMake(labelLeftOffset, labelTopOffset);
 
-    [self createPlaceholderLabel];
+    CGSize labelOffset = CGSizeMake(labelLeftOffset, labelTopOffset);
+    CGRect labelFrame = [self placeholderLabelFrameWithOffset:labelOffset];
+    [self createPlaceholderLabel:labelFrame];
 }
 
 
-#pragma mark - Placeholder label helper
+#pragma mark - Placeholder label helpers
 
 // Create our label:
-- (void)createPlaceholderLabel {
-    CGRect labelFrame = [self calculatePlaceholderLabelFrame];
-
+- (void)createPlaceholderLabel:(CGRect)labelFrame {
     self.placeholderLabel = [[UILabel alloc] initWithFrame:labelFrame];
     self.placeholderLabel.lineBreakMode = NSLineBreakByWordWrapping;
     self.placeholderLabel.numberOfLines = 0;
     self.placeholderLabel.font = self.font;
     self.placeholderLabel.backgroundColor = [UIColor clearColor];
     self.placeholderLabel.text = self.placeholderText;
-    // Manually matched to UITextField's placeholder text color.
+    // Color-matched to UITextField's placeholder text color:
     self.placeholderLabel.textColor = [UIColor colorWithWhite:0.71f alpha:1.0f];
 
+    // UIKit effects on the UITextView, like selection ranges
+    // and the cursor, are done in a view above the text view,
+    // so no need to order this below anything else.
+    // Add the label as a subview.
     [self addSubview:self.placeholderLabel];
 }
 
-
-- (CGRect)calculatePlaceholderLabelFrame {
-    return CGRectMake(self.labelOffset.width,
-                      self.labelOffset.height,
-                      self.bounds.size.width  - (2 * self.labelOffset.width),
-                      self.bounds.size.height - (2 * self.labelOffset.height));
+- (CGRect)placeholderLabelFrameWithOffset:(CGSize)labelOffset {
+    return CGRectMake(labelOffset.width,
+                      labelOffset.height,
+                      self.bounds.size.width  - (2 * labelOffset.width),
+                      self.bounds.size.height - (2 * labelOffset.height));
 }
 
+
 #pragma mark - Custom accessors
 
 - (void)setPlaceholderText:(NSString *)string {
@@ -105,16 +118,15 @@ - (void)setPlaceholderText:(NSString *)string {
 
 #pragma mark - UITextView subclass methods
 
-// Keep the placeholder label font in sync with the text view's
+// Keep the placeholder label font in sync with the view's text font.
 - (void)setFont:(UIFont *)font {
     // Call super.
     [super setFont:font];
 
     self.placeholderLabel.font = self.font;
 }
 
-
-// Keep placeholder label alignment in sync
+// Keep placeholder label alignment in sync with the view's text alignment.
 - (void)setTextAlignment:(NSTextAlignment)textAlignment {
     // Call super.
     [super setTextAlignment:textAlignment];
@@ -135,13 +147,14 @@ - (id)insertDictationResultPlaceholder {
     // Call super.
     id placeholder = [super insertDictationResultPlaceholder];
 
-    // Use .hidden (instead of alpha), since these events also trigger
-    // -[textChanged] (which has a different criteria by which it shows the label)
+    // Use -[setHidden] here instead of setAlpha:
+    // these events also trigger -[textChanged],
+    // which has a different criteria by which it shows the label,
+    // but we undeniably know we want this placeholder hidden.
     self.placeholderLabel.hidden = YES;
     return placeholder;
 }
 
-
 // Update visibility when dictation ends.
 - (void)removeDictationResultPlaceholder:(id)placeholder willInsertResult:(BOOL)willInsertResult {
     // Call super.
@@ -165,8 +178,7 @@ - (void)updatePlaceholderLabelVisibility {
     }
 }
 
-
-// When text is set or changed, update the label's visibility:
+// When text is set or changed, update the label's visibility.
 
 - (void)setText:(NSString *)text {
     // Call super.
@@ -175,10 +187,8 @@ - (void)setText:(NSString *)text {
     [self updatePlaceholderLabelVisibility];
 }
 
-
 - (void)textChanged:(NSNotification *)notification {
     [self updatePlaceholderLabelVisibility];
 }
 
-
 @end