修改占位符颜色

UIColor * placeHolderColor = [UIColor colorWithRed:153/255.0 green:153/255.0 blue:153/255.0 alpha:1.0];
self.textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:self.textField.placeholder attributes:@{NSForegroundColorAttributeName: placeHolderColor}];