iOS为View添加可视化属性

oc中使用IB_DESIGNABLE和IBInspectable
swift中使用@IBDesignable和@IBInspectable

IB_DESIGNABLE声明在类上，IBInspectable声明在属性上

IB_DESIGNABLE
@interface DesignDemoView : UIView
@property(nonatomic,assign) IBInspectable CGFloat scale;

IB_DESIGNABLE和IBInspectable两个效果不同，IB_DESIGNABLE用于将drawrect中写的效果显示在storyboard或者xib上，IBInspectable是在storyboard或者xib上添加一个可修改的属性

首先创建一个DesignDemoView类
头文件声明属性

#import <UIKit/UIKit.h>
IB_DESIGNABLE
@interface DesignDemoView : UIView
@property(nonatomic,assign) IBInspectable CGFloat cornerRadiu;
@end

//重写setter方法，用于设置圆角
-(void)setCornerRadiu:(CGFloat)cornerRadiu{
    self.layer.cornerRadius=cornerRadiu;
    self.layer.masksToBounds=YES;
}
//重写drawrect，在xib中会直接显示出hello
-(void)drawRect:(CGRect)rect{
    UIFont * font =[UIFont systemFontOfSize:15];
    [@"hello" drawInRect:CGRectMake(50, 10, 100, 100) withAttributes:@{NSFontAttributeName:font,NSForegroundColorAttributeName:[UIColor orangeColor]}];
}

xib中添加一个view，并设置custom class为DesignDemoView

shot.png

IBInspectable给DesignDemoView类添加了一个cornerRadiu属性，可以用于修改圆角

shot.png

shot.png