如何自定义UIPickerView中文本的大小和文本靠左或靠右显示？

需要重写UIPickerView中的

-(UIView*)pickerView:(UIPickerView*)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view

方法

示例代码如下

 //自定义uipickerview中的文字大小
 -(UIView*)pickerView:(UIPickerView*)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
 {
     UILabel *myView=nil;

     myView=[[UILabel alloc]initWithFrame:CGRectMake(0.0, 0.0, , )];
     myView.textAlignment=NSTextAlignmentRight;

     if (pickerView==self.SourcePicker) {
         myView.text=[_SourcePickerArray objectAtIndex:row];

     }else{
         myView.text=[_RoomPickerArray objectAtIndex:row];
     }
     myView.font=[UIFont systemFontOfSize:];
     myView.textColor=[UIColor blackColor];
     myView.backgroundColor=[UIColor clearColor];
     return  myView;

 }

另外注意，ios6之前调整文本靠左或者靠右对齐的代码为

mylabel.textAlignment= UITextAlignmentCenter;

在ios7以上版本需要改为

mylabel.textAlignment=NSTextAlignmentCenter;