前几天遇到一个问题：UITextfield 这个控件的属性placeholder 的字体大小无法修改.
网上的2种方法:一般只能修改掉 颜色，而对字体无效.
1
[textFieldsetValue:[UIColor redColor]forKeyPath:@"_placeholderLabel.textColor"]; [textFieldsetValue:[UIFontboldSystemFontOfSize:16]forKeyPath:@"_placeholderLabel.font"];
2 在iOS6.0之后提供的attributedPlaceholder属性：
[placeholder addAttribute:NSForegroundColorAttributeNamevalue:[UIColorredColor] range:NSMakeRange(0, holderText.length)];
[placeholder addAttribute:NSFontAttributeNamevalue:[UIFontboldSystemFontOfSize:16] range:NSMakeRange(0, holderText.length)];textField.attributedPlaceholder = placeholder;[cell.contentView addSubview:textField];
这 2种方法:一般只能修改掉 颜色，而对字体无效.
于是 写一个自己的 placeholder label属性.进行解决这个问题.
class MyTextField:UITextField {
private var _myPlaceHolderLabel = UILabel()
var myPlaceHolderLabel : UILabel {
get {
return _myPlaceHolderLabel
}
}
override init(frame: CGRect) {
super.init(frame: frame)
_myPlaceHolderLabel.text = text
_myPlaceHolderLabel.numberOfLines = 0;
_myPlaceHolderLabel.textColor = UIColor.lightGray
_myPlaceHolderLabel.sizeToFit()
self.addSubview(_myPlaceHolderLabel)
_myPlaceHolderLabel.font = UIFont.boldSystemFont(ofSize: 13)
_myPlaceHolderLabel.snp.makeConstraints { (make) in
make.top.bottom.left.right.equalToSuperview()
}
NotificationCenter.default.addObserver(self, selector: #selector(MyTextField.textFieldDidChange), name: NSNotification.Name.UITextFieldTextDidChange, object: self)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func textFieldDidChange(hidePlaceHolder:Bool) {
if (self.text?.characters.count)! > 0 || hidePlaceHolder{
_myPlaceHolderLabel.isHidden = true
}else {
_myPlaceHolderLabel.isHidden = false
}
}
}