iphone - UITextField - 在输入第一个字符后添加一个字符

Question

我有一个包含高度值的 UITextField。我想在用户输入 UITextField 时格式化字段的值。例如如果我想输入值“5 英尺 10”，流程将是:

1. Enter 5
2. " ft " is appended immediately after I type 5 with leading & trailing space.

我的代码是这样的:

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range       replacementString:(NSString *)string
{   

if ( [string isEqualToString:@""] ) return YES;

// currHeight Formatting
if ( textField == currHeight )  { 
   if (currHeight.text.length == 1) {   
        currHeight.text = [NSString stringWithFormat:@"%@ ft ", currHeight.text];    
        }
}
return YES; 
}

我卡在输入 5 时没有任何反应。我必须点击任何按钮才能附加“ft ”。

我可以在不点击任何东西的情况下执行此操作吗？

Answer 1

-shouldChangeCharactersInRange 在文本字段发生更改之前被调用，因此长度仍然为 0(请参阅 Using `textField:shouldChangeCharactersInRange:`, how do I get the text including the current typed character?)。试试这个:

- (BOOL)textField:(UITextField*)textField shouldChangeCharactersInRange:(NSRange)range
replacementString: (NSString*) string {
    if (textField == currHeight) {
        NSString *text = [textField.text stringByReplacingCharactersInRange:range
        withString: string];
        if (text.length == 1) { //or probably better, check if int
            textField.text = [NSString stringWithFormat: @"%@ ft ", text];
            return NO;
        }
    }
    return YES;
}