iOS 修改textField的placeholder的字体颜色、大小

1.

textField.placeholder =@"用户名";

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];

[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

2.

UIColor *color = [UIColor whiteColor];

_userName.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"用户名" attributes:@{NSForegroundColorAttributeName: color}];