在一个label中显示多行,自动换行

开发项目中，遇到一个动态显示detail page的问题。取的数据有的时候多有的时候少，而且还需要自动换行。计算行的高度，text的长度，大小等。
EventAddresslabel=[[UILabel
alloc]initWithFrame:CGRectMake(starttimelabel.frame.origin.x,
starttimelabel.frame.origin.y+distance,
270,
20)];
EventAddresslabel.backgroundColor=[UIColor
clearColor];
EventAddresslabel.textColor=[UIColor
whiteColor];
EventAddresslabel.font=[UIFont
systemFontOfSize:15];
EventAddresslabel.numberOfLines =0;
//this is used to determine how many lines this label will have.if =3,it means this
label's text will show 3 lines.if =0 ,it means that this label's text will show the line whate it needs.no limit.
EventAddresslabel.lineBreakMode =
UILineBreakModeWordWrap;// sys will change the line by word.aslo can be by character
for another value.
EventAddresslabel.text=[NSString
stringWithFormat:@"%@ %@,%@",cassetInfo.eventAddress,cassetInfo.city,cassetInfo.state];
[uiview
addSubview:EventAddresslabel];

CGSize EventAddresslabelsize = [EventAddresslabel.text
sizeWithFont:[UIFont
systemFontOfSize:15]
constrainedToSize:CGSizeMake(285,
[EventAddresslabel.text
length])
lineBreakMode:UILineBreakModeWordWrap];
[EventAddresslabel
setFrame:CGRectMake(EventAddresslabel.frame.origin.x,
EventAddresslabel.frame.origin.y,
290,EventAddresslabelsize.height+10)];

Description=[[UILabel
alloc]initWithFrame:CGRectMake(5,
EventAddresslabel.frame.origin.y+EventAddresslabel.frame.size.height,
320,
60)];
DescriptionactivityView = [[UIActivityIndicatorView
alloc]
initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
DescriptionactivityView.frame =
CGRectMake(140.f,
EventAddresslabel.frame.origin.y+30,
30.0f,
30.0f);
Londinglabel_1=[[UILabel
alloc]initWithFrame:CGRectMake(132,
Description.frame.origin.y+30,
80,
20)];
Labelflag=0;
Description.backgroundColor=[UIColor
clearColor];
Description.textColor=[UIColor
whiteColor];
Description.font=[UIFont
systemFontOfSize:15];
Description.numberOfLines =0;
Description.lineBreakMode =
UILineBreakModeWordWrap;
[uiview
addSubview:Description];