IOS Runtime的用法

什么是runtime？

1> runtime是一套底层的C语言API（包含很多强大实用的C语言数据类型、C语言函数）
2> 实际上，平时我们编写的OC代码，底层都是基于runtime实现的
* 也就是说，平时我们编写的OC代码，最终都是转成了底层的runtime代码（C语言代码）

runtime有啥用？

1> 能动态产生一个类、一个成员变量、一个方法
2> 能动态修改一个类、一个成员变量、一个方法
3> 能动态删除一个类、一个成员变量、一个方法

常见的函数、头文件

#import <objc/runtime.h> :           成员变量、类、方法
Ivar * class_copyIvarList :              获得某个类内部的所有成员变量
Method * class_copyMethodList :     获得某个类内部的所有方法
Method class_getInstanceMethod :   获得某个实例方法（对象方法，减号-开头）
Method class_getClassMethod :        获得某个类方法（加号+开头）
method_exchangeImplementations : 交换2个方法的具体实现

#import <objc/message.h> : 消息机制
objc_msgSend(....)

#import "HMViewController.h"
#import "HMPerson.h"
#import <objc/runtime.h>
#import <objc/message.h>

@interface HMViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *iconView1;
@property (weak, nonatomic) IBOutlet UIImageView *iconView2;

@property (nonatomic, strong) NSMutableArray *names;
@property (nonatomic, strong) NSArray *books;

@end

@implementation HMViewController

- (NSMutableArray *)names
{
    if (_names == nil) {
        self.names = [NSMutableArray array];
    }
    return _names;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

//    NSDictionary *info = @{@"name" : @"jack", @"age" : @10};
//
//    NSString *key = nil;
//
//    NSLog(@"%@", info[key]);

    NSMutableDictionary *info = [NSMutableDictionary dictionary];
    info[@"name"] = nil;

//    self.books = @[@"kiuhua", @"xxx"];
//
//    NSLog(@"%@", self.books[4]);

//    [self addName:@"jack"];
//    [self addName:@"rose"];
//    [self addName:@"jim"];
//
//    NSLog(@"%@", self.names[4]);
//    NSLog(@"%@", [self.names objectAtIndex:4]);
}

- (void)addName:(NSString *)name
{
    [self.names addObject:name];
}

- (void)imageSwizzle
{
    // 什么是iOS Swizzle？利用运行时函数交换2个方法的实现

    //    BOOL iOS7 = [[UIDevice currentDevice].systemVersion floatValue] >= 7.0;
    //    if (iOS7) {
    //        self.iconView1.image = [UIImage imageNamed:@"face_os7"];
    //        self.iconView2.image = [UIImage imageNamed:@"vip_os7"];
    //    } else {
    //        self.iconView1.image = [UIImage imageNamed:@"face"];
    //        self.iconView2.image = [UIImage imageNamed:@"vip"];
    //    }
    self.iconView1.image = [UIImage imageNamed:@"face"];
    self.iconView2.image = [UIImage imageNamed:@"vip"];
}

- (void)testRuntimeIvar
{
    // Ivar : 成员变量
    unsigned int count = ;
    // 获得所有的成员变量
    Ivar *ivars = class_copyIvarList([HMPerson class], &count);
    for (int i = ; i<count; i++) {
        // 取得i位置的成员变量
        Ivar ivar = ivars[i];
        const char *name = ivar_getName(ivar);
        const char *type = ivar_getTypeEncoding(ivar);
        NSLog(@"%d %s %s", i, name, type);
    }

    //    HMPerson *p = [[HMPerson alloc] init];
    //    objc_msgSend(p, @selector(setAge:), 20);

    //    NSLog(@"%d", p.age);
}

HMPerson.h /.m(获取所有成员变量)

#import <Foundation/Foundation.h>

@interface HMPerson : NSObject <NSCoding>
@property (nonatomic, assign) int age;
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) double height;
- (void)run;
@end

#import "HMPerson.h"
#import <objc/runtime.h>

@implementation HMPerson
- (void)run
{
    NSLog(@"run----");
}

- (void)encodeWithCoder:(NSCoder *)encoder
{
    unsigned int count = ;
    Ivar *ivars = class_copyIvarList([HMPerson class], &count);
    for (int i = ; i<count; i++) {
        // 取得i位置的成员变量
        Ivar ivar = ivars[i];
        const char *name = ivar_getName(ivar);
        NSString *key = [NSString stringWithUTF8String:name];
        [encoder encodeObject:[self valueForKeyPath:key] forKey:key];
    }
}

@end

UIImage+Extension(交换2个方法的实现)

#import <objc/runtime.h>

@implementation UIImage (Extension)
/**
 *  只要分类被装载到内存中，就会调用1次
 */
+ (void)load
{
    Method otherMehtod = class_getClassMethod(self, @selector(imageWithName:));
    Method originMehtod = class_getClassMethod(self, @selector(imageNamed:));
    // 交换2个方法的实现
    method_exchangeImplementations(otherMehtod, originMehtod);
}

+ (UIImage *)imageWithName:(NSString *)name
{
    BOOL iOS7 = [[UIDevice currentDevice].systemVersion floatValue] >= 7.0;
    UIImage *image = nil;
    if (iOS7) {
        NSString *newName = [name stringByAppendingString:@"_os7"];
        image = [UIImage imageWithName:newName];
    }

    if (image == nil) {
        image = [UIImage imageWithName:name];
    }
    return image;
}

@end

NSObject+Extension(交换2个方法的实现)

#import <objc/runtime.h>

@implementation NSObject(Extension)
+ (void)swizzleClassMethod:(Class)class originSelector:(SEL)originSelector otherSelector:(SEL)otherSelector
{
    Method otherMehtod = class_getClassMethod(class, otherSelector);
    Method originMehtod = class_getClassMethod(class, originSelector);
    // 交换2个方法的实现
    method_exchangeImplementations(otherMehtod, originMehtod);
}

+ (void)swizzleInstanceMethod:(Class)class originSelector:(SEL)originSelector otherSelector:(SEL)otherSelector
{
    Method otherMehtod = class_getInstanceMethod(class, otherSelector);
    Method originMehtod = class_getInstanceMethod(class, originSelector);
    // 交换2个方法的实现
    method_exchangeImplementations(otherMehtod, originMehtod);
}
@end

@implementation NSArray(Extension)
+ (void)load
{
    [self swizzleInstanceMethod:NSClassFromString(@"__NSArrayI") originSelector:@selector(objectAtIndex:) otherSelector:@selector(hm_objectAtIndex:)];
}

- (id)hm_objectAtIndex:(NSUInteger)index
{
    if (index < self.count) {
        return [self hm_objectAtIndex:index];
    } else {
        return nil;
    }
}

@end

@implementation NSMutableArray(Extension)
+ (void)load
{
    [self swizzleInstanceMethod:NSClassFromString(@"__NSArrayM") originSelector:@selector(addObject:) otherSelector:@selector(hm_addObject:)];
    [self swizzleInstanceMethod:NSClassFromString(@"__NSArrayM") originSelector:@selector(objectAtIndex:) otherSelector:@selector(hm_objectAtIndex:)];
}

- (void)hm_addObject:(id)object
{
    if (object != nil) {
        [self hm_addObject:object];
    }
}

- (id)hm_objectAtIndex:(NSUInteger)index
{
    if (index < self.count) {
        return [self hm_objectAtIndex:index];
    } else {
        return nil;
    }
}
@end