1. BSClassInfo.h文件

//
//  ClassInfo
//  BSClassInfo
//  Created by yuYue on 2019/2/2.
//  Copyright © 2019 yuYue. All rights reserved.
//#import <Foundation/Foundation.h>
#import <objc/runtime.h>NS_ASSUME_NONNULL_BEGIN@interface BSIvarInfo : NSObject
@property (assign, nonatomic, readonly) Ivar ivar;
@property (copy, nonatomic, readonly) NSString *name;
@property (assign, nonatomic, readonly) ptrdiff_t offset;
@property (copy, nonatomic, readonly) NSString *typeEncoding;- (instancetype)initWithIvar:(Ivar)ivar;
@end@interface BSMethodInfo : NSObject
@property (assign, nonatomic, readonly) Method method;
@property (copy, nonatomic, readonly) NSString *name;
@property (assign, nonatomic, readonly) SEL sel;
@property (assign, nonatomic, readonly) IMP imp;
@property (copy, nonatomic, readonly) NSString *typeEncoding;
@property (copy, nonatomic, readonly) NSString *returnTypeEncoding;
@property (copy, nonatomic, readonly) NSArray<NSString *> *argumentTypeEncoding;- (instancetype)initWithMethod:(Method)method;
@end@interface BSPropertyInfo : NSObject
@property (assign, nonatomic, readonly) objc_property_t property;
@property (copy, nonatomic, readonly) NSString *name;
@property (copy, nonatomic, readonly) NSString *typeEncoding;
@property (copy, nonatomic, readonly) NSString *ivarName;
@property (assign, nonatomic, readonly) SEL getter;
@property (assign, nonatomic, readonly) SEL setter;
@property (nullable, assign, nonatomic, readonly) Class cls;
@property (nullable, copy, nonatomic, readonly) NSArray<NSString *> *protocols;- (instancetype)initWithProperty:(objc_property_t)property;@end@interface BSClassInfo : NSObject
@property (assign, nonatomic, readonly) Class cls;
@property (assign, nonatomic, readonly) Class supCls;
@property (assign, nonatomic, readonly) Class metaCls;
@property (assign, nonatomic, readonly) BOOL isMeta;
@property (copy, nonatomic, readonly) NSString *name;
@property (nullable, strong, nonatomic, readonly) BSClassInfo *superClassInfo;@property (nullable, strong, nonatomic, readonly) NSDictionary<NSString *, BSIvarInfo *> *ivarInfos;
@property (nullable, strong, nonatomic, readonly) NSDictionary<NSString *, BSMethodInfo *> *methodInfos;
@property (nullable, strong, nonatomic, readonly) NSDictionary<NSString *, BSPropertyInfo *> *propertyInfos;- (instancetype)initWithClass:(Class)cls;
@endNS_ASSUME_NONNULL_END复制代码

1. BSClassInfo.m 文件

//
//  NSObject+BSClassInfo.m
//  ClassInfo
//
//  Created by yuYue on 2019/2/2.
//  Copyright © 2019 yuYue. All rights reserved.
//#import "BSClassInfo.h"@implementation BSIvarInfo- (instancetype)initWithIvar:(Ivar)ivar{if (!ivar) return nil;self = [super init];_ivar = ivar;const char * name = ivar_getName(ivar);if (name) {_name = [NSString stringWithUTF8String:name];}_offset = ivar_getOffset(ivar);const char * typeEncoding = ivar_getTypeEncoding(ivar);if (typeEncoding) {_typeEncoding = [NSString stringWithUTF8String:typeEncoding];}return self;
}
@end@implementation BSMethodInfo- (instancetype)initWithMethod:(Method)method{if(!method) return nil;self = [super init];_method = method;_sel = method_getName(method);const char *name = sel_getName(_sel);if (name) {_name = [NSString stringWithUTF8String:name];}_imp = method_getImplementation(method);const char *typeEncoding = method_getTypeEncoding(method);if (typeEncoding) {_typeEncoding = [NSString stringWithUTF8String:typeEncoding];}char *returnType = method_copyReturnType(method);if (returnType) {_returnTypeEncoding = [NSString stringWithUTF8String:returnType];free(returnType);}unsigned int argumentCount = method_getNumberOfArguments(method);if (argumentCount > 0) {NSMutableArray *arrM = [NSMutableArray array];for (int i = 0; i < argumentCount; i++) {char *argumentType = method_copyArgumentType(method, i);NSString *type = argumentType ? [NSString stringWithUTF8String:argumentType] : @"";[arrM addObject:type];free(argumentType);}_argumentTypeEncoding = arrM;}return self;
}@end@implementation BSPropertyInfo
- (instancetype)initWithProperty:(objc_property_t)property{if(!property) return nil;self = [super init];_property = property;const char *name  = property_getName(property);if (name) {_name = [NSString stringWithUTF8String:name];}if (_name) {_getter = NSSelectorFromString(_name);NSString *setter = [NSString stringWithFormat:@"set%@%@",[[_name substringToIndex:1]uppercaseString],[_name substringFromIndex:1]];_setter = NSSelectorFromString(setter);}unsigned int count;objc_property_attribute_t *attributs =  property_copyAttributeList(property, &count);for (int i = 0; i < count; i++) {switch (attributs[i].name[0]) {case 'T':{//typeEncoding_typeEncoding = [NSString stringWithUTF8String:attributs[i].value];if (*_typeEncoding.UTF8String == '@') {size_t len = strlen(_typeEncoding.UTF8String);if (len != 2) {//是对象NSScanner *scanner = [NSScanner scannerWithString:_typeEncoding];if (![scanner scanString:@"@\"" intoString:NULL]) continue;NSString *clsName = nil;if ([scanner scanUpToCharactersFromSet:[NSCharacterSet characterSetWithCharactersInString:@"\"<"] intoString:&clsName]) {_cls = NSClassFromString(clsName);}//protocolNSMutableArray *arrM = [NSMutableArray array];while ([scanner scanString:@"<" intoString:NULL]) {NSString *protocol;if ([scanner scanUpToString:@">" intoString:&protocol]) {if (protocol.length) {[arrM addObject:protocol];}}[scanner scanString:@">" intoString:NULL];}_protocols = arrM;}}}break;case 'V':{if (attributs[i].value) {_ivarName = [NSString stringWithUTF8String:attributs[i].value];}}break;default:break;}}return self;
}
@end@implementation BSClassInfo
- (instancetype)initWithClass:(Class)cls{if(!cls) return nil;self = [super init];_cls = cls;_supCls = class_getSuperclass(cls);_isMeta = class_isMetaClass(cls);if (!_isMeta) {_metaCls = objc_getMetaClass(class_getName(cls));}_name = [NSString stringWithUTF8String:class_getName(cls)];[self update];_superClassInfo = [[BSClassInfo alloc] initWithClass:_supCls];return self;
}- (void)update{_ivarInfos = nil;_methodInfos = nil;_propertyInfos = nil;//ivarClass cls = self.cls;unsigned int ivarCount = 0;NSMutableDictionary *dictMIvar = [NSMutableDictionary dictionary];Ivar *ivarList = class_copyIvarList(cls, &ivarCount);for (int i = 0; i < ivarCount; i++) {BSIvarInfo *ivarInfo = [[BSIvarInfo alloc] initWithIvar:ivarList[i]];[dictMIvar setObject:ivarInfo forKey:ivarInfo.name];}_ivarInfos = dictMIvar;free(ivarList);//methodNSMutableDictionary *dictMMethod = [NSMutableDictionary dictionary];unsigned int methodCount = 0;Method *methodList = class_copyMethodList(cls, &methodCount);for (int i = 0 ; i < methodCount; i++) {BSMethodInfo *methodInfo = [[BSMethodInfo alloc] initWithMethod:methodList[i]];[dictMMethod setObject:methodInfo forKey:methodInfo.name];}_methodInfos = dictMMethod;free(methodList);//propertyNSMutableDictionary *dictMProperty = [NSMutableDictionary dictionary];unsigned int propertyCount = 0;objc_property_t *propertyList = class_copyPropertyList(cls, &propertyCount);for (int i = 0; i < propertyCount; i++) {BSPropertyInfo *propertyInfo = [[BSPropertyInfo alloc] initWithProperty:propertyList[i]];[dictMProperty setObject:propertyInfo forKey:propertyInfo.name];}_propertyInfos = dictMProperty;free(propertyList);
}
@end
复制代码

1. 总结
   以上代码是读完YYModel中的YYClassInfo源码学到的利用runtime获取类的信息。YYClassInfo源代码中有关于缓存的部分，而我们的目的是抽取runtime部分，所以这里没有做缓存。有兴趣的小伙伴可以和YYClassInfo源代码做下对比会发现有些部分会有些少许改动。其实就是按照自己的习惯写出来的代码会和源代码有些不同，但都达到了获取类信息的目的。该代码有助于理解YYModel源码以及可以进一步学习runtime知识，一举两得。