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_NSConcreteStackBlock; //栈区
_NSConcreteGlobalBlock; //.data数据区
_NSConcreteMallocBlock; //堆区
_Block_object_assign //retain
_Block_object_dispose //release
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将栈区的block复制到堆区，用_Block_copy方法，注册到autoreleasepool中，然后返回该对象
tmp = _Block_copy(tmp);
return objc_autoreleaseReturnValue(tmp);
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// id为objc_object类型的结构体指针
typedef struct objc_object{
Class *isa;
} *id;
// Class为objc_class类型的结构体指针，与id类型结构一致
typedef struct objc_class{
Class isa;
} *Class;
struct Test{
Class isa;
int a;
int b;
};
struct class_t{
struct class_t *isa;
struct class_t *superclass;
Cache cache;
IMP *vtable;
uintptr_t data_NEVER_USE;
};
void (^block)(id obj);
{
id array = [NSMutableArray new];
block = [ ^(id obj){
[array addObject:obj];
NSLog(@"array: %@",array);
} copy ];
}
block([NSObject new]);
block([NSObject new]);
block([NSObject new]);
循环引用
typedef void(^Block)(void);
@interface Test: NSObject
{
Block _block;
}
@end
@implementation Test
-(instancetype)init{
self = [super init];
// 改为弱引用方式即可避免
id __weak weakSelf = self;
_block = ^{
NSLog(@"self = %@", self); //_block引用self，self拥有_block
NSLog(@"_var = %@", _var); //也会引起循环引用，相当于间接截获了self
//使用_var等同于self->_var
// 这样即可避免
id __weak obj = _val;
_block = ^{
NSLog(@"_val = %@", obj);
};
};
return self;
}
-(void)dealloc{
NSLog(@"dealloc");
}
@end
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id array = [NSMutableArray new];
void (^add)(void) = ^{
id obj = [NSObject new];
[array addObject:obj];
};
add();
NSLog(@"array: %@",array);
typedef int (^SumBlock)(int a, int b);
__block int result = 0;
SumBlock sum = ^(int a, int b){
result = a + b;
return result;
};
sum(1,2);
NSLog(@"result: %d", result);
typedef int (^SumBlock)(int a, int b);
SumBlock sum = ^(int a, int b){
return a + b;
};
NSLog(@"sum: %d", sum(1, 1));
void (^block)(int a);
block = ^(int a){
NSLog(@"block var: %d",a);
};
block(10);
^{
NSLog(@"block");
}();
^(int a){
NSLog(@"%d", a);
}(10);
int sum = ^(int a, int b){ return a + b; }(5, 1);
NSLog(@"sum: %d", sum);
