将Javascript转换为Objective C(数字的最后4位)

Question

请耐心听我编程。我对Objective C还很陌生。我想将以下javascript代码转换为Objective C。我只想显示路由和帐号的最后4位数字。

<script>
var routing = document.getElementById('routing_number');
var changed1 = document.getElementById('routing_number');
changed1.value = new Array(routing.value.length-3).join('x') + routing.value.substr(routing.value.length-4, 4);
var account = document.getElementById('account_number');
var changed2 = document.getElementById('account_number');
changed2.value = new Array(account.value.length-3).join('x') + account.value.substr(account.value.length-4, 4);
</script>

我在Objective C中尝试了以下部分代码，但没有成功。换句话说，我想把javascript中的内容准确地翻译成目标C。任何帮助都将不胜感激。

_routingText.text = [Utilities removeNullFromString:[response valueForKey:@"routing_number"]];
NSString *routing_number = _routingText.text;
routing_number = [routing_number substringToIndex:(routing_number.length - 4)];

Answer 1

我为任何想要答案的人找到了答案，答案如下。

NSString *routing_number = [Utilities removeNullFromString:[response valueForKey:@"routing_number"]];
NSString *last4Chr = [routing_number substringFromIndex: [routing_number length] - 4];
NSMutableString *mask = [[NSMutableString alloc]init];
for (int i=0; i<[routing_number length]-4; i++) 
{
[mask appendString:@"*"];
}
[mask appendString:last4Chr];
_routingText.text = mask;
NSString *account_number = [Utilities removeNullFromString:[response valueForKey:@"account_number"]];
NSString *last4Chr2 = [account_number substringFromIndex: [account_number length] - 4];
NSMutableString *mask2 = [[NSMutableString alloc]init];
for (int i=0; i<[account_number length]-4; i++) 
{
[mask2 appendString:@"*"];
}
[mask2 appendString:last4Chr2];
_acc_NumText.text = mask2;