通过富文本的方式添加行间距和字间距
//字间距
NSDictionary*toastLabelDic =@{NSKernAttributeName:@10.0f};
//行间距
NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
[paragraphStyle setLineSpacing:30];
NSDictionary*paragraphLabelDic =@{NSParagraphStyleAttributeName:paragraphStyle};
//富文本
NSMutableAttributedString*attributedString = [[NSMutableAttributedString alloc] initWithString:toastStr attributes:paragraphLabelDic];
