UITextview的高度适应有关问题

UITextview的高度适应问题
NSString *text=@"this is the test";CGSize constraintSize;constraintSize.width = rect1.size.width;constraintSize.height = MAXFLOAT;CGSize sizeFrame =[text sizeWithFont: [UIFont systemFontOfSize:16] constrainedToSize:constraintSize lineBreakMode: UILineBreakModeWordWrap];textview.text=text; [textView setFrame:CGRectMake(0, 0, 310, sizeFrame.height+40)];