label自适应文本大小

UILabel *label = [[UILabelalloc] initWithFrame:CGRectZero];

NSString *string = @"aa2fkoksdajfisd32323koiwejfskmfiweja2332e23ksdvjekosdko是是是是是是";

CGSize consSize = CGSizeMake(320, 2000);

CGSize size = [string sizeWithFont:[UIFontsystemFontOfSize:16] constrainedToSize:consSize];

label.numberOfLines = 0;

label.font = [UIFont systemFontOfSize:16];

label.text = string;

label.backgroundColor = [UIColorredColor];

label.frame = CGRectMake(0, 0, size.width, size.height);

[self.view addSubview:label];