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.h"
@interface 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;
@end
@implementation 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(didBeginEdit ing) name:UITextViewTextDidBeginEditingNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(didEndEditin g) name:UITextViewTextDidEndEditingNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textDidChan ge:) name:UITextViewTextDidChangeNotification object:self];
}
return self;
}
- (void)dealloc
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidBeginE ditingNotification object:self];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidEndEdi tingNotification object:self];
[[NSNotificationCenter defaultCenter] removeObserver:self name:UITextViewTextDidChang eNotification 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) {
https://www.doczj.com/doc/0d4764755.html,ingPlaceholder = NO;
NSRange range = [self.text rangeOfString:self.placeholder options:NSLiteralSearch];
if (range.location != NSNotFound) {
NSString *newText = [self.text stringByReplacingCharactersInRange:range withStr ing:@""];
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;
https://www.doczj.com/doc/0d4764755.html,ingPlaceholder = 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);
}
@end
CPTextViewPlaceholder.h
//
// CPTextViewPlaceholder.h
// Cassius Pacheco
//
// Created by Cassius Pacheco on 30/01/13.
// Copyright (c) 2013 Cassius Pacheco. All rights reserved. //
#import
@interface CPTextViewPlaceholder : UITextView
@property (nonatomic, strong) NSString *placeholder;
@end