iOS 设置控件圆角、文字、字体

以按钮为例：

UIButton btn = [UIButton new];

btn.layer.masksToBounds = YES;

btn.layer.cornerRadius = 10.0;

btn.layer.width = 2.0;

btn.layer.borderColor = [UIColor redColor].CGColor;

btn.layer.borderWidth = 2.0;

[btn setTitle:@"刷新" forState:UIControlStateNormal];

btn.titleLabel.font = [UIFont systemFontOfSize:15];