IOS 一个带有placeholder的UITextView

本文主要是介绍IOS 一个带有placeholder的UITextView，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

前言：IOS自带的UITextView并没有像UITextField自带placeholder属性，因此我们需要自己构造一个出来。

注：如果光标位置在中左，需要设置

self.automaticallyAdjustsScrollViewInsets = NO;

这个属性，这样子，光标位置就会在上左位置，出现这个问题是由于使用系统自带的UINavigationController导致的。

简单的使用，示例代码如下：

CGFloat textViewX = AdaptedHeight(15);

CGFloat textViewY = KHeight64 + AdaptedHeight(30);
CGFloat textViewH = (KScreenHeight - 2*textViewY)/3;
CGFloat textViewW = KScreenWidth - 2*textViewX;
IWTextView *textView = [[IWTextView alloc] initWithFrame:CGRectMake(textViewX, textViewY, textViewW, textViewH) placeHolder:@"说点什么..." maxLimitLength:0];
//是否隐藏字数统计控件
textView.isHidecountLabel = YES;
textView.textViewEndEditingBlock = ^(NSString *textStr){//结束编辑的时候调用
};
[self.view addSubview:textView];

自定义控件代码

#import <UIKit/UIKit.h>typedef void(^IWTextViewEndEditingBlock)(NSString *textStr);@interface IWTextView : UIView/**初始化对象@param frame          frame@param placeHolderStr 占位字符@param maxLimitLength 最大长度限制*/
- (id)initWithFrame:(CGRect)frame placeHolder:(NSString *)placeHolderStr maxLimitLength:(NSInteger)maxLimitLength;//默认显示
@property (nonatomic,assign) BOOL isHidecountLabel;@property (nonatomic,copy) IWTextViewEndEditingBlock textViewEndEditingBlock;@end

#import "IWTextView.h"@interface IWTextView ()<UITextViewDelegate>
{NSInteger _maxLimitLength;
}@property (nonatomic,strong) UILabel *placeholderLabel;@property (nonatomic,strong) UITextView *contentTextView;@property (nonatomic,strong) UILabel *countLabel;@end@implementation IWTextView- (instancetype)init
{self = [super init];if (self) {self.backgroundColor = [UIColor whiteColor];self.layer.borderWidth = KBorderWidth;self.layer.borderColor = KGreyColor.CGColor;self.layer.cornerRadius = 5;self.layer.masksToBounds = YES;}return self;
}- (id)initWithFrame:(CGRect)frame placeHolder:(NSString *)placeHolderStr maxLimitLength:(NSInteger)maxLimitLength
{//1.初始化对象IWTextView *textView = [self init];textView.frame = frame;_maxLimitLength = maxLimitLength;//2.占位LabelCGFloat placeholderLabelX = 15;CGFloat placeholderLabelY = 10;CGFloat placeholderLabelW = textView.frame.size.width - 2*placeholderLabelX;CGFloat placeholderLabelH = 20;self.placeholderLabel.frame = CGRectMake(placeholderLabelX, placeholderLabelY, placeholderLabelW, placeholderLabelH);self.placeholderLabel.text = placeHolderStr;[textView addSubview:self.placeholderLabel];//3.计算字数统计的宽高NSString *countStr;if (maxLimitLength == 0) {countStr = @"无字数限制";}else {countStr = [NSString stringWithFormat:@"当前可输入%ld字",(long)maxLimitLength];}CGRect countR = [countStr boundingRectWithSize:CGSizeMake(KScreenWidth*0.5, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:KFontCaption} context:nil];CGFloat countLabelW = countR.size.width;CGFloat countLabelH = countR.size.height;//4.添加UITextViewCGFloat contentTextViewX = 10;CGFloat contentTextViewY = 5;CGFloat contentTextViewW = textView.frame.size.width - 2*contentTextViewX;CGFloat contentTextViewH = textView.frame.size.height - 2*contentTextViewY - countLabelH;self.contentTextView.frame = CGRectMake(contentTextViewX, contentTextViewY, contentTextViewW, contentTextViewH);[textView insertSubview:self.contentTextView belowSubview:self.placeholderLabel];//5.添加字数统计CGFloat countLabelX = textView.frame.size.width - countLabelW - contentTextViewX;CGFloat countLabelY = CGRectGetMaxY(self.contentTextView.frame) - contentTextViewY;self.countLabel.frame = CGRectMake(countLabelX, countLabelY, countLabelW, countLabelH);self.countLabel.text = countStr;[textView addSubview:self.countLabel];return textView;
}- (UILabel *)placeholderLabel
{if (!_placeholderLabel) {_placeholderLabel = [[UILabel alloc] init];_placeholderLabel.font = KFontContent;_placeholderLabel.textColor = KGreyColor;}return _placeholderLabel;
}- (UITextView *)contentTextView
{if (!_contentTextView) {_contentTextView = [[UITextView alloc] init];_contentTextView.delegate = self;_contentTextView.textColor = KGreyColor54;_contentTextView.font = KFontContent;}return _contentTextView;
}- (UILabel *)countLabel
{if (!_countLabel) {_countLabel = [[UILabel alloc] init];_countLabel.font = KFontCaption;_countLabel.textColor = KGoldColor;_countLabel.textAlignment = NSTextAlignmentRight;}return _countLabel;
}- (void)setIsHidecountLabel:(BOOL)isHidecountLabel
{_isHidecountLabel = isHidecountLabel;self.countLabel.hidden = _isHidecountLabel;
}#pragma mark - UITextView代理
- (void)textViewDidChange:(UITextView *)textView
{if (textView.text.length == 0 || textView.text == nil) {self.placeholderLabel.hidden = NO;_countLabel.text = [NSString stringWithFormat:@"当前可输入%ld字",(long)_maxLimitLength];}else{self.placeholderLabel.hidden = YES;if (_maxLimitLength != 0) {NSString *toBeString = textView.text;UITextInputMode *mode = textView.textInputMode;NSString *lang = mode.primaryLanguage;if ([lang isEqualToString:@"zh-Hans"]) {UITextRange *selectedRange = [textView markedTextRange];UITextPosition *position = [textView positionFromPosition:selectedRange.start offset:0];if (!position && toBeString.length > _maxLimitLength) {textView.text = [toBeString substringToIndex:_maxLimitLength];}if (!position) {NSInteger count = _maxLimitLength - textView.text.length;_countLabel.text = [NSString stringWithFormat:@"当前可输入%ld字",(long)count];}}else {if (toBeString.length > _maxLimitLength) {textView.text = [toBeString substringToIndex:_maxLimitLength];}NSInteger count = _maxLimitLength - textView.text.length;_countLabel.text = [NSString stringWithFormat:@"当前可输入%ld字",(long)count];}}}
}- (void)textViewDidEndEditing:(UITextView *)textView
{if (_textViewEndEditingBlock) {_textViewEndEditingBlock(textView.text);}
}@end

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