实时限制输入方法很多 我个人钟爱使用正则表达式 比较灵活简单
NSString * regex = @"(^[a-zA-Z0-9]$)"; 限制只能输入字母和数字 其他限制类型可以参考正则语法
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
NSString * currentString = textField.text;
// 删除回退的时候返回yes
if (string.length == 0 && range.length == 1) {
return YES;
}
if (textField == self.vin) {
NSString * regex = @"(^[a-zA-Z0-9]$)";
NSPredicate * pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
BOOL isMatch = [pred evaluateWithObject:string];
BOOL lessThanMax = [currentString length] < 17;
return (isMatch && lessThanMax)?YES:NO;
}
if (textField == self.engineNo) {
NSString * regex = @"(^[a-zA-Z0-9]$)";
NSPredicate * pred = [NSPredicate predicateWithFormat:@"SELF MATCHES %@", regex];
BOOL isMatch = [pred evaluateWithObject:string];
//BOOL lessThanMax = [currentString length] < 6;
return isMatch?YES:NO;
}
return YES;
}
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