//使用kvc修改placeholder 的字體顏色
[textField ?setValue:[UIColor ?redColor] ?forKeyPath:@"_placeholderLabel.textColor"];
[textField ?setValue:[UIFont ?boldSystemFontOfSize:16] ?forKeyPath:@"_placeholderLabel.font"];
//swift寫法
pwdField.setValue(UIColor.colorWithHexString("0xbbbbbb"), forKeyPath:"placeholderLabel.textColor")// _placeholderLabel.textColor也行pwdField.setValue(UIFont.systemFontOfSize(13.0),forKeyPath:"placeholderLabel.font")
// 使用kvc替換UITextField中的 placeholderLabel
YBLabel* placeholderLabel = [YBLabel ?labelWithTitle:@"賬號(hào)" ?font:18 ? textColor:[UIColor ?whiteColor] ?alignment:NSTextAlignmentCenter];
[textField ?setValue:placeholderLabel ?forKeyPath:@"_placeholderLabel"];
