对于runtime我们前边介绍了消息机制,我们并没有介绍runtime的API.
1.runtime的API
一. runtime关于类的API
①. 动态创建一个类（参数：父类，类名，额外的内存空间)
Class objc_allocateClassPair(Class superclass, const char *name, size_t extraBytes)
②. 注册一个类（要在类注册之前添加成员变量）
void objc_registerClassPair(Class cls)
③. 销毁一个类
void objc_disposeClassPair(Class cls)
例:
// 建一个命令行工程
#import <Foundation/Foundation.h>
#import <objc/runtime.h>
void run(id self, SEL _cmd) {
NSLog(@"_____ %@ - %@", self, NSStringFromSelector(_cmd));
}
int main(int argc, const char * argv[]) {
@autoreleasepool {
// insert code here...
// 动态创建一个类
Class newClass = objc_allocateClassPair([NSObject class], "CSDog", 0);
// 添加属性
class_addIvar(newClass, "_age", 4, 1, @encode(int));
class_addIvar(newClass, "_weight", 4, 1, @encode(int));
// 添加方法
class_addMethod(newClass, @selector(run), (IMP)run, "v@:");
// 注册类
objc_registerClassPair(newClass);
id dog = [[newClass alloc] init];
[dog setValue:@10 forKey:@"_age"];
[dog setValue:@20 forKey:@"_weight"];
[dog run];
NSLog(@"%@ %@", [dog valueForKey:@"_age"], [dog valueForKey:@"_weight"]);
// 在不需要这个类时释放
objc_disposeClassPair(newClass);
}
return 0;
}
注意:运用runtime动态创建一个类,注意一下需要在动态添加属性之后再注册类.(已经注册的类不能动态添加属性)
④. 获取isa指向的Class
Class object_getClass(id obj)
⑤. 设置isa指向的Class
Class object_setClass(id obj, Class cls)
⑥. 判断一个OC对象是否为Class
BOOL object_isClass(id obj)
例:
@interface CSPersion : NSObject
- (void)run;
@end
@implementation CSPersion
- (void)run {
NSLog(@"%s", __func__);
}
@end
@interface CSCar : NSObject
- (void)run;
@end
@implementation CSCar
- (void)run {
NSLog(@"%s", __func__);
}
@end
int main(int argc, const char * argv[]) {
@autoreleasepool {
// insert code here...
CSPersion *persion = [[CSPersion alloc] init];
[persion run];
object_setClass(persion, [CSCar class]);
[persion run];
object_getClass([CSPersion class]);
NSLog(@"%p %p", object_getClass([CSPersion class]), [CSPersion class]);
NSLog(@"%d %d %d",
object_isClass(persion),
object_isClass([CSPersion class]),
object_isClass(object_getClass([CSPersion class]))
);
}
return 0;
}
⑦. 判断一个Class是否为元类
BOOL class_isMetaClass(Class cls)
⑧. 获取父类
Class class_getSuperclass(Class cls)
2. runtime关于成员变量的API
①. 获取一个实例变量信息
Ivar class_getInstanceVariable(Class cls, const char *name)
②. 获取成员变量的相关信息
const char *ivar_getName(Ivar v)
const char *ivar_getTypeEncoding(Ivar v)
例:
@interface CSPersion : NSObject
@property (assign, nonatomic) int ID;
@property (assign, nonatomic) int weight;
@property (assign, nonatomic) int age;
@property (copy, nonatomic) NSString *name;
- (void)run;
@end
int main(int argc, const char * argv[]) {
@autoreleasepool {
// insert code here...
// 1.获取成员变量信息
Ivar ageIvar = class_getInstanceVariable([CSPersion class], "_age");
NSLog(@"%s %s",ivar_getName(ageIvar),ivar_getTypeEncoding(ageIvar));
}
return 0;
}
③. 设置和获取成员变量的值
void object_setIvar(id obj, Ivar ivar, id value)
id object_getIvar(id obj, Ivar ivar)
例:
@interface CSPersion : NSObject
@property (assign, nonatomic) int ID;
@property (assign, nonatomic) int weight;
@property (assign, nonatomic) int age;
@property (copy, nonatomic) NSString *name;
- (void)run;
@end
int main(int argc, const char * argv[]) {
@autoreleasepool {
// 2. 设置和获取成员变量的值
CSPersion *persion = [[CSPersion alloc] init];
Ivar nameIvar = class_getInstanceVariable([CSPersion class], "_name");
Ivar ageIvar = class_getInstanceVariable([CSPersion class], "_age");
object_setIvar(persion, nameIvar, @"123");
object_setIvar(persion, ageIvar, (__bridge id)(void *)10);
NSLog(@"%@ %d", persion.name, persion.age);
}
return 0;
}
④. 动态添加成员变量（已经注册的类是不能动态添加成员变量的）
BOOL class_addIvar(Class cls, const char * name, size_t size, uint8_t alignment,
const char * types)
例:
@interface CSPersion : NSObject
@property (assign, nonatomic) int ID;
@property (assign, nonatomic) int weight;
@property (assign, nonatomic) int age;
@property (copy, nonatomic) NSString *name;
- (void)run;
@end
int main(int argc, const char * argv[]) {
@autoreleasepool {
// 动态创建一个类
Class newClass = objc_allocateClassPair([NSObject class], "CSDog", 0);
// 添加属性
class_addIvar(newClass, "_age", 4, 1, @encode(int));
class_addIvar(newClass, "_weight", 4, 1, @encode(int));
// 添加方法
class_addMethod(newClass, @selector(run), (IMP)run, "v@:");
// 注册类
objc_registerClassPair(newClass);
id dog = [[newClass alloc] init];
[dog setValue:@10 forKey:@"_age"];
[dog setValue:@20 forKey:@"_weight"];
[dog run];
NSLog(@"%@ %@", [dog valueForKey:@"_age"], [dog valueForKey:@"_weight"]);
// 在不需要这个类时释放
objc_disposeClassPair(newClass);
}
return 0;
}
⑤. 拷贝实例变量列表（最后需要调用free释放）
Ivar *class_copyIvarList(Class cls, unsigned int *outCount)
例:
@interface CSPersion : NSObject
@property (assign, nonatomic) int ID;
@property (assign, nonatomic) int weight;
@property (assign, nonatomic) int age;
@property (copy, nonatomic) NSString *name;
- (void)run;
@end
int main(int argc, const char * argv[]) {
@autoreleasepool {
// 4.成员变量的数量
unsigned int count;
Ivar *ivars = class_copyIvarList([CSPersion class], &count);
for (int i = 0; i < count; i++) {
// 取出i位置的成员变量
Ivar ivar = ivars[I];
NSLog(@"%s %s", ivar_getName(ivar), ivar_getTypeEncoding(ivar));
}
free(ivars);
}
return 0;
}
实际应用:
A. 修改textfield的占位字的属性
a.运用runtime获取成员变量的方法:
for (int i = 0; i < count; i++) {
// 取出i位置的成员变量
Ivar ivar = ivars[I];
NSLog(@"%s %s", ivar_getName(ivar), ivar_getTypeEncoding(ivar));
}
b.然后再次修改
self.textField.placeholder = @"请输入用户名";
[self.textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
B. 字典转换成模型
a.利用Runtime遍历所有的属性或者成员变量
b.利用KVC设值
字典转换成模型代码.png
3. runtime关于属性的API
①. 获得一个实例方法、类方法
Method class_getInstanceMethod(Class cls, SEL name)
Method class_getClassMethod(Class cls, SEL name)
②. 方法实现相关操作
IMP class_getMethodImplementation(Class cls, SEL name)
IMP method_setImplementation(Method m, IMP imp)
void method_exchangeImplementations(Method m1, Method m2)
③. 拷贝方法列表（最后需要调用free释放）
Method *class_copyMethodList(Class cls, unsigned int *outCount)
④. 动态添加方法
BOOL class_addMethod(Class cls, SEL name, IMP imp, const char *types)
⑤. 动态替换方法
IMP class_replaceMethod(Class cls, SEL name, IMP imp, const char *types)
⑥. 获取方法的相关信息（带有copy的需要调用free去释放）
SEL method_getName(Method m)
IMP method_getImplementation(Method m)
const char *method_getTypeEncoding(Method m)
unsigned int method_getNumberOfArguments(Method m)
char *method_copyReturnType(Method m)
char *method_copyArgumentType(Method m, unsigned int index)
⑦. 选择器相关
const char *sel_getName(SEL sel)
SEL sel_registerName(const char *str)
⑧. 用block作为方法实现
IMP imp_implementationWithBlock(id block)
id imp_getBlock(IMP anImp)
BOOL imp_removeBlock(IMP anImp)
4. 方法替换
一般我们方法交换实现都是用的method_exchangeImplementations实现的.
一. 按钮的点击交换方法
如果需要监听所有按钮的点击事件
NS_CLASS_AVAILABLE_IOS(2_0) @interface UIButton : UIControl <NSCoding>
- (void)addTarget:(nullable id)target action:(SEL)action forControlEvents:(UIControlEvents)controlEvents;
- (void)sendAction:(SEL)action to:(nullable id)target forEvent:(nullable UIEvent *)event;
UIButton继承自UIControl，并且添加点击事件方法addTarget:action:forControlEvents最终是调用sendAction:to:forEvent方法，所以交换该方法即可。
实际实现代码:(UIControl的类扩展)
#import "UIControl+Extension.h"
#import <objc/runtime.h>
@implementation UIControl (Extension)
+ (void)load {
// hork:钩子函数
Method method1 = class_getInstanceMethod(self, @selector(sendAction:to:forEvent:));
Method method2 = class_getInstanceMethod(self, @selector(cs_sendAction:to:forEvent:));
method_exchangeImplementations(method1, method2);
}
- (void)cs_sendAction:(SEL)action to:(id)target forEvent:(UIEvent *)event {
NSLog(@"%@-%@-%@", self, target, NSStringFromSelector(action));
// 调用系统原理的实现
[self cs_sendAction:action to:target forEvent:event];
if ([self isKindOfClass:[UIButton class]]) {
NSLog(@"拦截了所有按钮的事件");
}
}
@end
二. 防止数组插入nil值,引起崩溃.
下边的代码如果在运行的过程中就会引起崩溃.
NSString *obj = nil;
NSMutableArray *array = [NSMutableArray array];
[array addObject:@"jack"];
[array insertObject:obj atIndex:0];
NSLog(@"%@", array);
使用交换方法实现防止数组插入nil引起的崩溃
#import "NSMutableArray+Extension.h"
#import <objc/runtime.h>
@implementation NSMutableArray (Extension)
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
// 类簇：NSString、NSArray、NSDictionary，真实类型是其他类型
Class cls = NSClassFromString(@"__NSArrayM");
Method method1 = class_getInstanceMethod(cls, @selector(insertObject:atIndex:));
Method method2 = class_getInstanceMethod(cls, @selector(cs_insertObject:atIndex:));
method_exchangeImplementations(method1, method2);
});
}
- (void)cs_insertObject:(id)anObject atIndex:(NSUInteger)index {
if (anObject == nil) {
return;
}
[self cs_insertObject:anObject atIndex:index];
}
@end
三. 防止字典中的key=nil值,引起崩溃.
NSString *obj = nil;
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
dict[@"name"] = @"jack";
dict[obj] = @"rose";
dict[@"age"] = obj;
NSLog(@"%@", dict);
如果上边的程序运行就会发生崩溃.
#import "NSMutableDictionary+Extension.h"
#import <objc/runtime.h>
@implementation NSMutableDictionary (Extension)
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
Class cls = NSClassFromString(@"__NSDictionaryM");
Method method1 = class_getInstanceMethod(cls, @selector(setObject:forKeyedSubscript:));
Method method2 = class_getInstanceMethod(cls, @selector(cs_setObject:forKeyedSubscript:));
method_exchangeImplementations(method1, method2);
Class cls2 = NSClassFromString(@"__NSDictionaryI");
Method method3 = class_getInstanceMethod(cls2, @selector(objectForKeyedSubscript:));
Method method4 = class_getInstanceMethod(cls2, @selector(cs_objectForKeyedSubscript:));
method_exchangeImplementations(method3, method4);
});
}
- (void)cs_setObject:(id)obj forKeyedSubscript:(id<NSCopying>)key {
if (!key) {
return;
}
[self cs_setObject:obj forKeyedSubscript:key];
}
- (id)cs_objectForKeyedSubscript:(id)key {
if (!key) {
return nil;
}
return [self cs_objectForKeyedSubscript:key];
}
@end
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