設定placeholder的字型顏色

//設定字型顏色

[self.searchTextField setValue:[UIColor colorWithRed:0.50 green:0.50 blue:0.50 alpha:1.0] forKeyPath:@"_placeholderLabel.textColor"];
   

//設定字型大小

[self.searchTextField setValue:[UIFont systemFontOfSize:15] forKeyPath:@"_placeholderLabel.font"];