1、字数限制
[[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(textFiledEditChanged:)
name:@"UITextFieldTextDidChangeNotification"
object:textField];
#define kMaxLength 5
-(void)textFiledEditChanged:(NSNotification *)obj{
UITextField *textField = (UITextField *)obj.object;
NSString *toBeString = textField.text;
NSString *lang = [textField textInputMode].primaryLanguage; // 键盘输入模式
if ([lang isEqualToString:@"zh-Hans"]) { // 简体中文输入，包括简体拼音，健体五笔，简体手写
UITextRange *selectedRange = [textField markedTextRange];
//获取高亮部分
UITextPosition *position = [textField positionFromPosition:selectedRange.start offset:0];
// 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 > kMaxLength) {
textField.text = [toBeString substringToIndex:kMaxLength];
}
}
// 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
else{
if (toBeString.length > kMaxLength) {
textField.text = [toBeString substringToIndex:kMaxLength];
}
}
}