NSObject+YYAdd的学习 NSObject+YYAdd的学习

文章图片
图片来之网络看到这个分类，直接无法想象，还对NSObject进行了一些自己方法的封装。写了那么多年的代码从来没有用到过或想到过，想要对NSObject进行扩展。YY大神，你可以的。
INIT_INV 在实现方法中，首先看到的是一个宏定义：

#define INIT_INV(_last_arg_, _return_) \ NSMethodSignature * sig = [self methodSignatureForSelector:sel]; \ if (!sig) { [self doesNotRecognizeSelector:sel]; return _return_; } \ NSInvocation *inv = [NSInvocation invocationWithMethodSignature:sig]; \ if (!inv) { [self doesNotRecognizeSelector:sel]; return _return_; } \ [inv setTarget:self]; \ [inv setSelector:sel]; \ va_list args; \ va_start(args, _last_arg_); \ [NSObject setInv:inv withSig:sig andArgs:args]; \ va_end(args);

将方法

- (id)performSelectorWithArgs:(SEL)sel, ...{ INIT_INV(sel, nil); [inv invoke]; return [NSObject getReturnFromInv:inv withSig:sig]; }

展开为：

- (id)performSelectorWithArgs:(SEL)sel, ... { NSMethodSignature * sig = [self methodSignatureForSelector:sel]; if (!sig) { [self doesNotRecognizeSelector:sel]; return nil; } NSInvocation *inv = [NSInvocation invocationWithMethodSignature:sig]; if (!inv) { [self doesNotRecognizeSelector:sel]; return nil; } [inv setTarget:self]; [inv setSelector:sel]; va_list args; va_start(args, sel); [NSObject setInv:inv withSig:sig andArgs:args]; va_end(args); [inv invoke]; return [NSObject getReturnFromInv:inv withSig:sig]; }

其中的

- (NSMethodSignature *)methodSignatureForSelector:(SEL)aSelector;

的作用是生成一个有效的方法签名。在runtime中objc_msgSend调用时，查找SEL的IML的过程：

文章图片
图片来之网络
根据NSMethodSignature创建NSInvocation实例，

+ (NSInvocation *)invocationWithMethodSignature:(NSMethodSignature *)sig;

. 为进行
forwardInvocation:准备。

[NSObject setInv:inv withSig:sig andArgs:args];

调用了方法： 【NSObject+YYAdd的学习】

+ (void)setInv:(NSInvocation *)inv withSig:(NSMethodSignature *)sig andArgs:(va_list)args { NSUInteger count = [sig numberOfArguments]; for (int index = 2; index < count; index++) { char *type = (char *)[sig getArgumentTypeAtIndex:index]; while (*type == 'r' || // const *type == 'n' || // in *type == 'N' || // inout *type == 'o' || // out *type == 'O' || // bycopy *type == 'R' || // byref *type == 'V') { // oneway type++; // cutoff useless prefix }BOOL unsupportedType = NO; switch (*type) { case 'v': // 1: void case 'B': // 1: bool case 'c': // 1: char / BOOL case 'C': // 1: unsigned char case 's': // 2: short case 'S': // 2: unsigned short case 'i': // 4: int / NSInteger(32bit) case 'I': // 4: unsigned int / NSUInteger(32bit) case 'l': // 4: long(32bit) case 'L': // 4: unsigned long(32bit) { // 'char' and 'short' will be promoted to 'int'. int arg = va_arg(args, int); [inv setArgument:&arg atIndex:index]; } break; case 'q': // 8: long long / long(64bit) / NSInteger(64bit) case 'Q': // 8: unsigned long long / unsigned long(64bit) / NSUInteger(64bit) { long long arg = va_arg(args, long long); [inv setArgument:&arg atIndex:index]; } break; case 'f': // 4: float / CGFloat(32bit) { // 'float' will be promoted to 'double'. double arg = va_arg(args, double); float argf = arg; [inv setArgument:&argf atIndex:index]; } break; case 'd': // 8: double / CGFloat(64bit) { double arg = va_arg(args, double); [inv setArgument:&arg atIndex:index]; } break; case 'D': // 16: long double { long double arg = va_arg(args, long double); [inv setArgument:&arg atIndex:index]; } break; case '*': // char * case '^': // pointer { void *arg = va_arg(args, void *); [inv setArgument:&arg atIndex:index]; } break; case ':': // SEL { SEL arg = va_arg(args, SEL); [inv setArgument:&arg atIndex:index]; } break; case '#': // Class { Class arg = va_arg(args, Class); [inv setArgument:&arg atIndex:index]; } break; case '@': // id { id arg = va_arg(args, id); [inv setArgument:&arg atIndex:index]; } break; case '{': // struct { if (strcmp(type, @encode(CGPoint)) == 0) { CGPoint arg = va_arg(args, CGPoint); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(CGSize)) == 0) { CGSize arg = va_arg(args, CGSize); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(CGRect)) == 0) { CGRect arg = va_arg(args, CGRect); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(CGVector)) == 0) { CGVector arg = va_arg(args, CGVector); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(CGAffineTransform)) == 0) { CGAffineTransform arg = va_arg(args, CGAffineTransform); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(CATransform3D)) == 0) { CATransform3D arg = va_arg(args, CATransform3D); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(NSRange)) == 0) { NSRange arg = va_arg(args, NSRange); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(UIOffset)) == 0) { UIOffset arg = va_arg(args, UIOffset); [inv setArgument:&arg atIndex:index]; } else if (strcmp(type, @encode(UIEdgeInsets)) == 0) { UIEdgeInsets arg = va_arg(args, UIEdgeInsets); [inv setArgument:&arg atIndex:index]; } else { unsupportedType = YES; } } break; case '(': // union { unsupportedType = YES; } break; case '[': // array { unsupportedType = YES; } break; default: // what?! { unsupportedType = YES; } break; }if (unsupportedType) { // Try with some dummy type...NSUInteger size = 0; NSGetSizeAndAlignment(type, &size, NULL); #define case_size(_size_) \ else if (size <= 4 * _size_ ) { \ struct dummy { char tmp[4 * _size_]; }; \ struct dummy arg = va_arg(args, struct dummy); \ [inv setArgument:&arg atIndex:index]; \ } if (size == 0) { } case_size( 1) case_size( 2) case_size( 3) case_size( 4) case_size( 5) case_size( 6) case_size( 7) case_size( 8) case_size( 9) case_size(10) case_size(11) case_size(12) case_size(13) case_size(14) case_size(15) case_size(16) case_size(17) case_size(18) case_size(19) case_size(20) case_size(21) case_size(22) case_size(23) case_size(24) case_size(25) case_size(26) case_size(27) case_size(28) case_size(29) case_size(30) case_size(31) case_size(32) case_size(33) case_size(34) case_size(35) case_size(36) case_size(37) case_size(38) case_size(39) case_size(40) case_size(41) case_size(42) case_size(43) case_size(44) case_size(45) case_size(46) case_size(47) case_size(48) case_size(49) case_size(50) case_size(51) case_size(52) case_size(53) case_size(54) case_size(55) case_size(56) case_size(57) case_size(58) case_size(59) case_size(60) case_size(61) case_size(62) case_size(63) case_size(64) else { /* Larger than 256 byte?! I don't want to deal with this stuff up... Ignore this argument. */ struct dummy {char tmp; }; for (int i = 0; i < size; i++) va_arg(args, struct dummy); NSLog(@"YYKit performSelectorWithArgs unsupported type:%s (%lu bytes)", [sig getArgumentTypeAtIndex:index],(unsigned long)size); } #undef case_size} } }

根据多个入参的第3个参数开始，不同的字符设置不同的数据类型。

[inv invoke];

调用方法。然后执行[NSObject getReturnFromInv:inv withSig:sig]，根据标志转化为不同的数据类型，返回不同类型的值。

+ (id)getReturnFromInv:(NSInvocation *)inv withSig:(NSMethodSignature *)sig { NSUInteger length = [sig methodReturnLength]; if (length == 0) return nil; char *type = (char *)[sig methodReturnType]; while (*type == 'r' || // const *type == 'n' || // in *type == 'N' || // inout *type == 'o' || // out *type == 'O' || // bycopy *type == 'R' || // byref *type == 'V') { // oneway type++; // cutoff useless prefix }#define return_with_number(_type_) \ do { \ _type_ ret; \ [inv getReturnValue:&ret]; \ return @(ret); \ } while (0)switch (*type) { case 'v': return nil; // void case 'B': return_with_number(bool); case 'c': return_with_number(char); case 'C': return_with_number(unsigned char); case 's': return_with_number(short); case 'S': return_with_number(unsigned short); case 'i': return_with_number(int); case 'I': return_with_number(unsigned int); case 'l': return_with_number(int); case 'L': return_with_number(unsigned int); case 'q': return_with_number(long long); case 'Q': return_with_number(unsigned long long); case 'f': return_with_number(float); case 'd': return_with_number(double); case 'D': { // long double long double ret; [inv getReturnValue:&ret]; return [NSNumber numberWithDouble:ret]; }; case '@': { // id void *ret; [inv getReturnValue:&ret]; return (__bridge id)(ret); }; case '#': { // Class Class ret = nil; [inv getReturnValue:&ret]; return ret; }; default: { // struct / union / SEL / void* / unknown const char *objCType = [sig methodReturnType]; char *buf = calloc(1, length); if (!buf) return nil; [inv getReturnValue:buf]; NSValue *value = https://www.it610.com/article/[NSValue valueWithBytes:buf objCType:objCType]; free(buf); return value; }; } #undef return_with_number }

swizzle 交换实例和类方法 + (BOOL)swizzleInstanceMethod:(SEL)originalSel with:(SEL)newSel 交换实例方法
在交互实例方法之前，需要先添加方法的实现，然后再调用method_exchangeImplementations(Method _Nonnull m1, Method _Nonnull m2)。
+ (BOOL)swizzleClassMethod:(SEL)originalSel with:(SEL)newSel 交换类方法
感觉将runtime的使用都封装了一层。一直觉得Runtime没有用处，或者是没有机会去优化代码，一直在码代码。希望那天可以改造下代码，用用高大上的runtime。
KVO 监听key path后执行block，并retain了block。提供了根据key path移除block或移除所有的block。并且支持相同的key，保存不同的block。
封装了系统的KVO，比系统的KVO使用上方便了很多。
在移除block的时候使用了

NSMutableDictionary *dic = [self _yy_allNSObjectObserverBlocks]; [dic enumerateKeysAndObjectsUsingBlock: ^(NSString *key, NSArray *arr, BOOL *stop) { [arr enumerateObjectsUsingBlock: ^(id obj, NSUInteger idx, BOOL *stop) { [self removeObserver:obj forKeyPath:key]; }]; }]; [dic removeAllObjects];

采用了枚举的方式列举所有的值，并进行移除。
// END