ios-UITextView的placeHolder的设置

我在用UITextView的时候，默认是不能设置placeholder的，于是网上找了一些资料，最后找到了一个别人写的自定义类，拿来用用，顺便分享一下。CPTextViewPlaceholder.m/ CPTextViewPlaceholder.m/ Cassius Pacheco/ Created by Cassius Pacheco on 30/01/13./ Copyright (c) 2013 Cassius Pacheco. All rights reserved./#import CPTextViewPlaceholder.hinterface CPTextViewPlaceholder()property (nonatomic) UITextAutocorrectionType originalCorrection;property (nonatomic, strong) UIColor *placeholderColor;property (nonatomic, strong) UIColor *originalTextColor;property (nonatomic, getter = isUsingPlaceholder) BOOL usingPlaceholder;property (nonatomic, getter = isSettingPlaceholder) BOOL settingPlaceholder;endimplementation CPTextViewPlaceholder#pragma mark -#pragma mark Life Cycle method- (id)initWithCoder:(NSCoder *)aDecoder if (self = super initWithCoder:aDecoder) self.placeholderColor = UIColor lightGrayColor; self.originalCorrection = self.autocorrectionType; self.originalTextColor = super.textColor; NSNotificationCenter defaultCenter addObserver:self selector:selector(didBeginEditing) name:UITextViewTextDidBeginEditingNotification object:nil; NSNotificationCenter defaultCenter addObserver:self selector:selector(didEndEditing) name:UITextViewTextDidEndEditingNotification object:nil; NSNotificationCenter defaultCenter addObserver:self selector:selector(textDidChange:) name:UITextViewTextDidChangeNotification object:self; return self;- (void)dealloc NSNotificationCenter defaultCenter removeObserver:self name:UITextViewTextDidBeginEditingNotification object:self; NSNotificationCenter defaultCenter removeObserver:self name:UITextViewTextDidEndEditingNotification object:self; NSNotificationCenter defaultCenter removeObserver:self name:UITextViewTextDidChangeNotification object:self;- (void)layoutSubviews super layoutSubviews; /Fixes iOS 5.x cursor when becomeFirstResponder if (UIDevice currentDevice.systemVersion.floatValue 6.000000) if (self.isUsingPlaceholder & self.isFirstResponder) self.text = ; #pragma mark -#pragma mark Notifications- (void)didBeginEditing if (self.isUsingPlaceholder) self sendCursorToBeginning; - (void)didEndEditing if (self.text.length = 0) self setupPlaceholder; - (void)textDidChange:(NSNotification *)notification /self.text received the placeholder text by CPTex tViewPlaceholder if (self.isSettingPlaceholder) return; if (self.text.length = 0) self setupPlaceholder; return; if (self.isUsingPlaceholder) self.usingPlaceholder = NO; NSRange range = self.text rangeOfString:self.placeholder options:NSLiteralSearch; if (range.location != NSNotFound) NSString *newText = self.text stringByReplacingCharactersInRange:range withString:; super.textColor = self.originalTextColor; super.autocorrectionType = self.originalCorrection; /User pasted a text equals to placeholder or setText was called if (newText isEqualToString:self.placeholder) self sendCursorToEnd; /this is necessary for iOS 5.x else if (newText.length = 0) self setupPlaceholder; return; self.text = newText; - (BOOL)canPerformAction:(SEL)action withSender:(id)sender if (self.isUsingPlaceholder & action != selector(paste:) return NO; return super canPerformAction:action withSender:sender;#pragma mark - Getters and Setters- (void)setAutocorrectionType:(UITextAutocorrectionType)autocorrectionType super setAutocorrectionType:autocorrectionType; self.originalCorrection = autocorrectionType;- (void)setPlaceholder:(NSString *)placeholder _placeholder = placeholder; if (self.isUsingPlaceholder | self.text.length = 0) self setupPlaceholder; - (void)setTextColor:(UIColor *)textColor super setTextColor:textColor; self.originalTextColor = textColor;- (void)setSelectedRange:(NSRange)selectedRange if (self.isUsingPlaceholder) self sendCursorToBeginning; else super setSelectedRange:selectedRange; - (void)setSelectedTextRange:(UITextRange *)selectedTextRange if (self.isUsingPlaceholder) self sendCursorToBeginning; else super setSelectedTextRange:selectedTextRange; #pragma mark -#pragma mark Utilities methods- (void)setupPlaceholder super.autocorrectionType = UITextAutocorrectionTypeNo; self.usingPlaceholder = YES; self.settingPlaceholder = YES; self.text = self.placeholder; self.settingPlaceholder = NO; super.textColor = self.placeholderColor; self sendCursorToBeginning;- (void)sendCursorToBeginning self performSelector:selector(cursorToBeginning) withObject:nil afterDelay:0.01;- (void)cursorToBeginning super.selectedRange = NSMakeRange(0, 0);- (void)sendCursorToEnd self performSelector:selector(cursorToEnd) withObject:nil afterDelay:0.01;- (void)cursorToEnd super.selectedRange = NSMakeRange(self.text.length, 0);endCPTextViewPlaceholder.h/ CPTe