对 textField 添加监测事件
[self.nameTextField addTarget:self action:@selector(textFieldValueChange:) forControlEvents:UIControlEventEditingChanged];
实现监测事件
NSInteger kMaxLength =16;
NSString*toBeString = textField.text;
NSString *lang = [[UIApplication sharedApplication]textInputMode].primaryLanguage;
if([lang isEqualToString:@"zh-Hans"]) {
UITextRange*selectedRange = [textField markedTextRange];
//获取高亮部分
UITextPosition*position = [textField positionFromPosition:selectedRange.start offset:0];
if (!position) {// 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(toBeString.length> kMaxLength) {
textField.text= [toBeString substringToIndex:kMaxLength];
}
}else{//有高亮选择的字符串，则暂不对文字进行统计和限制
}
}else{//中文输入法以外的直接对其统计限制即可，不考虑其他语种情况
if(toBeString.length> kMaxLength) {
textField.text= [toBeString substringToIndex:kMaxLength];
}
}
