设置label中placeHolder的字体大小和颜色
//设置placeholder的颜色和字体
[self.textField setValue:[UIColor whiteColor] forKeyPath:@"_placeholderLabel.textColor"];
[self.textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];
nvm use --delete-prefix iojs-v3.3.1 --silent
解决node npm command not found 问题
