UITextField 只能输入数字、一个小数点、只能有两位小数

//textField.text 输入之前的值 string 输入的字符
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
BOOL isHaveDian;
if ([textField1.text rangeOfString:@"."].location==NSNotFound) {
isHaveDian=NO;
}
if ([string length]>0)
{
unichar single=[string characterAtIndex:0];//当前输入的字符
if ((single >='0' && single<='9') || single=='.')//数据格式正确
{
//首字母不能为0和小数点
if([textField1.text length]==0){
if(single == '.'){
//[self alertView:@"亲，第一个数字不能为小数点"];
[textField1.text stringByReplacingCharactersInRange:range withString:@""];
return NO;
}
if (single == '0') {
//[self alertView:@"亲，第一个数字不能为0"];
[textField1.text stringByReplacingCharactersInRange:range withString:@""];
return NO;
}
}
if (single=='.')
{
if(!isHaveDian)//text中还没有小数点
{
isHaveDian=YES;
return YES;
}else
{
//[self alertView:@"亲，您已经输入过小数点了"];
[textField1.text stringByReplacingCharactersInRange:range withString:@""];
return NO;
}
}
else
{
if (isHaveDian)//存在小数点
{
//判断小数点的位数
NSRange ran=[textField1.text rangeOfString:@"."];
int tt=range.location-ran.location;
if (tt <= 2){
return YES;
}else{
//[self alertView:@"亲，您最多输入两位小数"];
return NO;
}
}
else
{
return YES;
}
}
}else{//输入的数据格式不正确
[self alertView:@"亲，您输入的格式不正确"];
[textField1.text stringByReplacingCharactersInRange:range withString:@""];
return NO;
}
}
else
{
return YES;
}
}