如何更改工程内最少的代码修改系统UISwitch的大小和样式

网上搜了一下，基本都是讲的如何自定义UISwitch控件。我今天来写一篇如何不更改（或最少的更改）原有工程里各个类关于UISwitch的声明、设置、调用代码，平滑的将系统UISwitch样式大小更改为客户需要求展示的样式。

看一下系统的UISwitch的展示效果

系统的UISwitch的提供的属性和方法：

方法很少，能让开发者修改的地方也很少：

1.frame是修改不了的

2.通过动画的方式可以放大缩小实现改变大小的效果，但是里面圆圈和外部的比例还是变不了

3.圆圈的颜色无法改变

为了将工程中所有用到这个控件的地方都改变其展示样式，

1.需要自定义一个控件，采用 UIImageView + UIButton的方式，UIImageView展示的是类似椭圆形图片，UIButton是上面的圆圈。通过点击button用动画来移动位置并更改背景图。

2.需要实现的方法和声明的属性（和系统的基本一致）

@property(nullable, nonatomic, strong) UIColor *onTintColor;

//@property(nullable, nonatomic, strong) UIColor *thumbTintColor;

@property(nonatomic,getter=isOn) BOOL on;

- (instancetype)init；

- (void)setOn:(BOOL)on animated:(BOOL)animated;

3.在pch文件 加上

#import "PublicSwitchView.h"
#define UISwitch PublicSwitchView

4.实现原理：通过写和系统一样的方法名来达到只更改类名的效果，通过宏定义一次更换所有地方的类名。

具体代码

////  PublicSwitchView.h//  Demo////  Created by yfc on 2017/10/14.//  Copyright © 2017年 yfc. All rights reserved.//#import <UIKit/UIKit.h>@interface PublicSwitchView : UIControl{    UIImageView *imageview;    UIButton *btn;}@property(nullable, nonatomic, strong) UIColor *onTintColor;//@property(nullable, nonatomic, strong) UIColor *thumbTintColor;@property(nonatomic,getter=isOn) BOOL on;- (void)setOn:(BOOL)on animated:(BOOL)animated;@end

////  PublicSwitchView.m//  Demo////  Created by yfc on 2017/10/14.//  Copyright © 2017年 yfc. All rights reserved.//#import "PublicSwitchView.h"#import "UIView+Utils.h"@implementation PublicSwitchView- (instancetype)init{        CGRect frame = CGRectMake(0, 0, 50, 25);        if (self = [super initWithFrame:frame]) {        self.backgroundColor = [UIColor clearColor];                //        //椭圆背景        //        imageview = [[UIImageView alloc]initWithFrame:frame];        imageview.image = [UIImage imageNamed:@"graySwitch"];        [self addSubview:imageview];                //        //圆圈        //        double height = frame.size.height - 7;        btn = [[UIButton alloc]initWithFrame:CGRectMake(5, 0, height, height)];        btn.layer.cornerRadius = btn.width / 2.0;        btn.backgroundColor = [UIColor whiteColor];        [btn addTarget:self action:@selector(btnClicked:) forControlEvents:UIControlEventTouchUpInside];        btn.centerY = frame.size.height / 2.0;        btn.userInteractionEnabled = YES;        [self addSubview:btn];                        [self addTarget:self action:@selector(btnClicked:) forControlEvents:UIControlEventTouchUpInside];        self.userInteractionEnabled = YES;    }    return self;    }////大小固定//- (void)setFrame:(CGRect)frame{    CGRect frame_ = CGRectMake(frame.origin.x, frame.origin.y, 50, 25);    [super setFrame:frame_];}////点击事件//- (void)btnClicked:(UIButton *)btneee{        [UIView animateWithDuration:0.25 animations:^{        if (btn.left < 6) {            btn.right = self.frame.size.width - 5;            self.on = YES;            imageview.image = [UIImage imageNamed:@"purpleSwitch"];            //            //发送点击事件            //            [self sendActionsForControlEvents:UIControlEventValueChanged];        }else{            btn.left = 5;            imageview.image = [UIImage imageNamed:@"graySwitch"];            self.on = NO;            //            //发送点击事件            //            [self sendActionsForControlEvents:UIControlEventValueChanged];        }            }];        }////带有动画的设置开关状态//- (void)setOn:(BOOL)on{        _on = on;        [UIView animateWithDuration:0.25 animations:^{        if (on == YES) {            btn.right = self.frame.size.width - 5;            imageview.image = [UIImage imageNamed:@"purpleSwitch"];                    }else{            btn.left = 5;            imageview.image = [UIImage imageNamed:@"graySwitch"];                    }    }];}////设置不可点击//- (void)setEnabled:(BOOL)enabled{        [super setEnabled:enabled];        if (enabled == NO) {        [self setOn:NO animated:NO];        imageview.image = [UIImage imageNamed:@"enabledSwitch"];        btn.backgroundColor = [UIColor colorWithRed:254/255.0 green:255/255.0 blue:255/255.0 alpha:1];            }}////是否带有动画的设置开关状态//- (void)setOn:(BOOL)on animated:(BOOL)animated;{        if (animated == YES) {        self.on = on;    }else{        _on = on;        if (on == YES) {            btn.right = self.frame.size.width - 5;            imageview.image = [UIImage imageNamed:@"purpleSwitch"];                    }else{            btn.left = 5;            imageview.image = [UIImage imageNamed:@"graySwitch"];                    }    }    }- (void)dealloc{    }@end

下面是效果图

最后：如果需求变化，又要使用系统的样式：屏蔽掉两句话即可