UITextView 也是较长用的控件之一，唯一问题就是没有占位符
本文介绍：
1、UITextView 添加占位符
2、算textview输入情况下的字符数，解决实现限制字符数时，计算不准的问题
直接上代码：
UITextView+Category.h
#import <UIKit/UIKit.h>
#import <objc/runtime.h>
@interface UITextView (Category)<UITextViewDelegate>
@property (nonatomic, strong) UITextView *placeHolderTextView;
/**
* @brief 占位符
*/
- (void)add_PlaceHolder:(NSString *)placeHolder;
/**
* @brief 当前选中的字符串范围
*
* @return NSRange
*/
- (NSRange)selectedRange;
/**
* @brief 选中所有文字
*/
- (void)selectAllText;
/**
* @brief 选中指定范围的文字
*
* @param range NSRange范围
*/
- (void)setSelectedRange:(NSRange)range;
// 用于计算textview输入情况下的字符数，解决实现限制字符数时，计算不准的问题
- (NSInteger)getInputLengthWithText:(NSString *)text;
UITextView+Category.m
#import "UITextView+Category.h"
static const char *phTextView = "placeHolderTextView";
@implementation UITextView (Category)
/**
* @brief 占位符
*/
- (UITextView *)placeHolderTextView {
return objc_getAssociatedObject(self, phTextView);
}
- (void)setPlaceHolderTextView:(UITextView *)placeHolderTextView {
objc_setAssociatedObject(self, phTextView, placeHolderTextView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (void)add_PlaceHolder:(NSString *)placeHolder {
if (![self placeHolderTextView]) {
self.delegate = self;
UITextView *textView = [[UITextView alloc] initWithFrame:self.bounds];
textView.autoresizingMask = UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth;
textView.font = self.font;
textView.backgroundColor = [UIColor clearColor];
textView.textColor = [UIColor grayColor];
textView.userInteractionEnabled = NO;
textView.text = placeHolder;
[self addSubview:textView];
[self setPlaceHolderTextView:textView];
}
}
# pragma mark -
# pragma mark - UITextViewDelegate
- (void)textViewDidBeginEditing:(UITextView *)textView {
self.placeHolderTextView.hidden = YES;
// if (self.textViewDelegate) {
//
// }
}
- (void)textViewDidEndEditing:(UITextView *)textView {
if (textView.text && [textView.text isEqualToString:@""]) {
self.placeHolderTextView.hidden = NO;
}
}
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
NSInteger textLength = [textView getInputLengthWithText:text];
if (textLength > 20) {
// 超过20个字可以删除
if ([text isEqualToString:@""]) {
return YES;
}
return NO;
}
return YES;
}
- (void)textViewDidChange:(UITextView *)textView
{
if ([textView getInputLengthWithText:nil] > 20) {
textView.text = [textView.text substringToIndex:20];
}
}
/**
* @brief 当前选中的字符串范围
*
* @return NSRange
*/
- (NSRange)selectedRange
{
UITextPosition* beginning = self.beginningOfDocument;
UITextRange* selectedRange = self.selectedTextRange;
UITextPosition* selectionStart = selectedRange.start;
UITextPosition* selectionEnd = selectedRange.end;
NSInteger location = [self offsetFromPosition:beginning toPosition:selectionStart];
NSInteger length = [self offsetFromPosition:selectionStart toPosition:selectionEnd];
return NSMakeRange(location, length);
}
/**
* @brief 选中所有文字
*/
- (void)selectAllText {
UITextRange *range = [self textRangeFromPosition:self.beginningOfDocument toPosition:self.endOfDocument];
[self setSelectedTextRange:range];
}
/**
* @brief 选中指定范围的文字
*
* @param range NSRange范围
*/
- (void)setSelectedRange:(NSRange)range {
UITextPosition *beginning = self.beginningOfDocument;
UITextPosition *startPosition = [self positionFromPosition:beginning offset:range.location];
UITextPosition *endPosition = [self positionFromPosition:beginning offset:NSMaxRange(range)];
UITextRange *selectionRange = [self textRangeFromPosition:startPosition toPosition:endPosition];
[self setSelectedTextRange:selectionRange];
}
//https://github.com/pclion/TextViewCalculateLength
// 用于计算textview输入情况下的字符数，解决实现限制字符数时，计算不准的问题
- (NSInteger)getInputLengthWithText:(NSString *)text
{
NSInteger textLength = 0;
//获取高亮部分
UITextRange *selectedRange = [self markedTextRange];
if (selectedRange) {
NSString *newText = [self textInRange:selectedRange];
textLength = (newText.length + 1) / 2 + [self offsetFromPosition:self.beginningOfDocument toPosition:selectedRange.start] + text.length;
} else {
textLength = self.text.length + text.length;
}
return textLength;
}
@end
用法
UITextView * textView =[[UITextView alloc]initWithFrame:CGRectMake(30, 100, KScreenWidth-60, 250)];
textView.backgroundColor = [UIColor lightGrayColor];
textView.font = [UIFont systemFontOfSize:18];
[textView add_PlaceHolder:@"请输入内心独白（20字以内）~"];
[self.view addSubview:textView];
效果
9E07218F-AB43-414E-9304-523644A4F575.png
我是写代码的凡，如有错误，欢迎指正！🙂🙂🙂
