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//
// UITextView+LengthLimit.m
// Gengmei
//
// Created by wangyang on 2017/3/9.
// Copyright © 2017年 更美互动信息科技有限公司. All rights reserved.
//
#import "UITextView+LengthLimit.h"
#import <objc/runtime.h>
@implementation UITextView (LimitBase)
- (NSInteger)maxTextLength {
NSNumber *length = objc_getAssociatedObject(self, @selector(maxTextLength));
return length.integerValue;
}
- (void)setMaxTextLength:(NSInteger)maxTextLength {
objc_setAssociatedObject(self, @selector(maxTextLength), @(maxTextLength), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
- (NSInteger)textLength {
NSNumber *length = objc_getAssociatedObject(self, @selector(textLength));
return length.integerValue;
}
- (void)setTextLength:(NSInteger)textLength {
objc_setAssociatedObject(self, @selector(textLength), @(textLength), OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
@end
@implementation UITextView (SimpleLimit)
- (void)s_textViewDidChange {
NSString *toBeString = self.text;
UITextRange *selectedRange = [self markedTextRange];
UITextPosition *position = [self positionFromPosition:selectedRange.start offset:0];
NSInteger length = self.textLength;
// 没有高亮选择的字，则对已输入的文字进行字数统计和限制
if (!position){
if (toBeString.length > self.maxTextLength){
NSRange rangeIndex = [toBeString rangeOfComposedCharacterSequenceAtIndex:self.maxTextLength];
if (rangeIndex.length == 1){
self.text = [toBeString substringToIndex:self.maxTextLength];
} else{
NSRange rangeRange = [toBeString rangeOfComposedCharacterSequencesForRange:NSMakeRange(0, self.maxTextLength)];
self.text = [toBeString substringWithRange:rangeRange];
}
length = self.text.length;
} else {
NSString *selectedText = [self textInRange:selectedRange];
length = self.text.length - selectedText.length;
}
}
if (length > self.maxTextLength) {
self.textLength = self.maxTextLength;
} else {
self.textLength = length;
}
}
@end
@implementation UITextView (ComplexLimit)
- (BOOL)c_shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text
{
if (text.length==0) { //Delete any cases
if(range.length > 1){
//Delete whole word
}
else if(range.length == 1){
//Delete single letter
}
else if(range.length == 0){
//Tap delete key when textField empty
}
return YES;
}
UITextRange *selectedRange = [self markedTextRange];
//获取高亮部分
UITextPosition *pos = [self positionFromPosition:selectedRange.start offset:0];
//获取高亮部分内容
// NSString * selectedtext = [self textInRange:selectedRange];
//如果有高亮且当前字数开始位置小于最大限制时允许输入
if (selectedRange && pos) {
NSInteger startOffset = [self offsetFromPosition:self.beginningOfDocument toPosition:selectedRange.start];
NSInteger endOffset = [self offsetFromPosition:self.beginningOfDocument toPosition:selectedRange.end];
NSRange offsetRange = NSMakeRange(startOffset, endOffset - startOffset);
if (offsetRange.location < self.maxTextLength) {
return YES;
}
else
{
return NO;
}
}
NSString *comcatstr = [self.text stringByReplacingCharactersInRange:range withString:text];
NSInteger canInputLen = self.maxTextLength - comcatstr.length;
if (canInputLen >= 0)
{
return YES;
}
else
{
NSInteger len = text.length + canInputLen;
//防止当text.length + caninputlen < 0时，使得rg.length为一个非法最大正数出错
NSRange rg = {0,MAX(len,0)};
if (rg.length > 0)
{
NSString *s = @"";
//判断是否只普通的字符或asc码(对于中文和表情返回NO)
BOOL asc = [text canBeConvertedToEncoding:NSASCIIStringEncoding];
if (asc) {
s = [text substringWithRange:rg];//因为是ascii码直接取就可以了不会错
}
else
{
__block NSInteger idx = 0;
__block NSString *trimString = @"";//截取出的字串
//使用字符串遍历，这个方法能准确知道每个emoji是占一个unicode还是两个
[text enumerateSubstringsInRange:NSMakeRange(0, [text length])
options:NSStringEnumerationByComposedCharacterSequences
usingBlock: ^(NSString* substring, NSRange substringRange, NSRange enclosingRange, BOOL* stop) {
NSInteger steplen = substring.length;
if (idx >= rg.length) {
*stop = YES; //取出所需要就break，提高效率
return ;
}
trimString = [trimString stringByAppendingString:substring];
idx = idx + steplen;//这里变化了，使用了字串占的长度来作为步长
}];
s = trimString;
}
//rang是指从当前光标处进行替换处理(注意如果执行此句后面返回的是YES会触发didchange事件)
[self setText:[self.text stringByReplacingCharactersInRange:range withString:s]];
//既然是超出部分截取了，那一定是最大限制了。
self.textLength = self.maxTextLength;
}
return NO;
}
}
- (void)c_textViewDidChange
{
UITextRange *selectedRange = [self markedTextRange];
//获取高亮部分
UITextPosition *pos = [self positionFromPosition:selectedRange.start offset:0];
//如果在变化中是高亮部分在变，就不要计算字符了
if (selectedRange && pos) {
return;
}
NSString *nsTextContent = self.text;
NSInteger existTextNum = nsTextContent.length;
if (existTextNum > self.maxTextLength)
{
//截取到最大位置的字符(由于超出截部分在should时被处理了所在这里这了提高效率不再判断)
NSString *s = [nsTextContent substringToIndex:self.maxTextLength];
[self setText:s];
self.textLength = self.maxTextLength;
} else {
self.textLength = existTextNum;
}
}
@end