UIAlertController设置title颜色

想要给UIAlertController title 设置颜色。首先看了UIAlertController的属性，并没有对title颜色对应的属性。然后通过runtime获取了其多有属性发现，UIAlertController有一个私有属性attributedTitle。然后通过富文本实现。方法如下:

-(void)alertWithTitle:(NSString*)title andMessage:(NSString*)message{

UIAlertController*alertVC=[UIAlertControlleralertControllerWithTitle:@""message:messagepreferredStyle:(UIAlertControllerStyleAlert)];

NSDictionary* dic=@{NSForegroundColorAttributeName:[UIColorredColor],

NSFontAttributeName:[UIFontsystemFontOfSize:17],

NSExpansionAttributeName:@(0.2),

};

NSMutableAttributedString*attributedStr=[[NSMutableAttributedStringalloc]initWithString:titleattributes:dic];

[alertVCsetValue:attributedStrforKey:@"attributedTitle"];

UIAlertAction*ac=[UIAlertActionactionWithTitle:@"取消"style:(UIAlertActionStyleDefault)handler:^(UIAlertAction*_Nonnullaction) {

}];

[alertVCaddAction:ac];

[selfpresentViewController:alertVCanimated:YEScompletion:nil];

}