/*
label.font = [UIFont fontWithName:@"Helvetica-Bold" size:20];//加粗
label.font = [UIFont fontWithName:@"Helvetica-Oblique" size:20];//加斜
label.font = [UIFont fontWithName:@"Helvetica-BoldOblique" size:20];//又粗又斜
*/
链接：https://www.jianshu.com/p/d6384e67db52