self.textNumLab爲顯示剩餘字數的label
#pragma mark -限制病情描述輸入字數(最多不超過255個字)
- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text{
//不支持系統表情的輸入
if ([[textView textInputMode] primaryLanguage]==nil||[[[textView textInputMode] primaryLanguage]isEqualToString:@"emoji"]) {
returnNO;
}
UITextRange *selectedRange = [textView markedTextRange];
//獲取高亮部分
UITextPosition *pos = [textView positionFromPosition:selectedRange.startoffset:0];
//獲取高亮部分內容
//NSString * selectedtext = [textView textInRange:selectedRange];
//如果有高亮且當前字數開始位置小於最大限制時允許輸入
if (selectedRange && pos) {
NSInteger startOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.start];
NSInteger endOffset = [textView offsetFromPosition:textView.beginningOfDocument toPosition:selectedRange.end];
NSRange offsetRange =NSMakeRange(startOffset, endOffset - startOffset);
if (offsetRange.location <MAX_LIMIT_NUMS) {
return YES;
}else{
return NO;
}
}
NSString *comcatstr = [textView.text stringByReplacingCharactersInRange:range withString:text];
NSInteger caninputlen =MAX_LIMIT_NUMS - comcatstr.length;
if (caninputlen >=0){
return YES;
}else{
NSInteger len = text.length + caninputlen;
//防止當text.length + caninputlen < 0時,使得rg.length爲一個非法最大正數出錯
NSRange rg = {0,MAX(len,0)};
if (rg.length >0){
NSString *s =@"";
//判斷是否只普通的字符或asc碼(對於中文和表情返回NO)
BOOL asc = [text canBeConvertedToEncoding:NSASCIIStringEncoding];
if (asc) {
s = [text substringWithRange:rg];//因爲是ascii碼直接取就可以了不會錯
}else{
__block NSInteger idx =0;
__block NSString *trimString =@"";//截取出的字串
//使用字符串遍歷,這個方法能準確知道每個emoji是佔一個unicode還是兩個
[text enumerateSubstringsInRange:NSMakeRange(0, [text length])
options:NSStringEnumerationByComposedCharacterSequences
usingBlock: ^(NSString* substring,NSRange substringRange,NSRange enclosingRange,BOOL* stop) {
if (idx >= rg.length) {
*stop =YES;//取出所需要就break,提高效率
return ;
}
trimString = [trimString stringByAppendingString:substring];
idx++;
}];
s = trimString;
}
//rang是指從當前光標處進行替換處理(注意如果執行此句後面返回的是YES會觸發didchange事件)
[textView setText:[textView.text stringByReplacingCharactersInRange:rangewithString:s]];
//既然是超出部分截取了,哪一定是最大限制了。
self.textNumLab.text = [NSString stringWithFormat:@"%d/%ld",0,(long)MAX_LIMIT_NUMS];
}
returnNO;
}
}
#pragma mark -顯示當前可輸入字數/總字數
- (void)textViewDidChange:(UITextView *)textView{
UITextRange *selectedRange = [textView markedTextRange];
//獲取高亮部分
UITextPosition *pos = [textView positionFromPosition:selectedRange.startoffset:0];
//如果在變化中是高亮部分在變,就不要計算字符了
if (selectedRange && pos) {
return;
}
NSString *nsTextContent = textView.text;
NSInteger existTextNum = nsTextContent.length;
if (existTextNum >MAX_LIMIT_NUMS){
//截取到最大位置的字符(由於超出截部分在should時被處理了所在這裏這了提高效率不再判斷)
NSString *s = [nsTextContent substringToIndex:MAX_LIMIT_NUMS];
[textViewsetText:s];
}
//不讓顯示負數
self.textNumLab.text = [NSStringstringWithFormat:@"%ld/%d",MAX(0,MAX_LIMIT_NUMS - existTextNum),MAX_LIMIT_NUMS];
}
參考地址:http://www.it165.net/pro/html/201505/39736.html