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下面一段代码给大家介绍ios mrc 下 block 循环引用问题
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//注意此__block会复制一份指针出来 一次原始的指针如果置为nil的话,此处复制出来的指针还是野指针
__block __typeof(self)weakself = self;
//__weak __typeof(self)weakself = self;
//__weak person *weakself = self;
void (^block)(void) = ^(void){
//nslog(@"name --> is %@", self.name);
//nslog(@"name --> is %@", weakself.name);
//这样判断会crash 此时weakself为野指针
//weakself 这时候是个野指针。。。野指针也是指针对吧？反正，这个野指针并不为null,虽然它指向的内存并未有什么鸟用，
//然而代码并不知道。所以 执行[weakself dosomething]; 必然闪退。
//注意此__block会复制一份指针出来 一次原始的指针如果置为nil的话,此处复制出来的指针还是野指针
// if (weakself) {
// nslog(@"name --> is %@", weakself.name);
// }
//malloc(22);
// malloc_zon
//这并没有什么卵用。。。weakself 已经是野指针 照样crash
// __strong __typeof(weakself) strongself = weakself;
// if (weakself) {
// nslog(@"name --> is %@", strongself.name);
// }
if (malloc_zone_from_ptr(weakself)) {
nslog(@"name --> is %@", weakself.name);
}
//
// viewcontroller.m
// test_mrc_block_self_01
//
// created by jeffasd on 2017/12/1.
// copyright © 2017年 jeffasd. all rights reserved.
//
#import "viewcontroller.h"
#import "person.h"
@interface viewcontroller ()
@property (nonatomic, copy) nsstring *name;
@end
@implementation viewcontroller
- (void)viewdidload {
[super viewdidload];
self.view.backgroundcolor = [uicolor whitecolor];
self.name = @"xiaoming";
}
- (void)touchesbegan:(nsset<uitouch *> *)touches withevent:(uievent *)event{
self.view.backgroundcolor = [uicolor cyancolor];
// void (^block)(void) = ^(void){
// nslog(@"name --> is %@", self.name);
// };
//
//
//
// for (int i = 0; i < 30; i++) {
// block();
// }
person *xiaoming = [[person alloc] init];
//[xiaoming retain];
[xiaoming release];
// xiaoming = nil;
xiaoming = null;
}
- (void)didreceivememorywarning {
[super didreceivememorywarning];
// dispose of any resources that can be recreated.
}
@end
//
// person.m
// test_mrc_block_self_01
//
// created by jeffasd on 2017/12/1.
// copyright © 2017年 jeffasd. all rights reserved.
//
#import "person.h"
#include <malloc/malloc.h>
@interface person ()
@property (nonatomic, copy) nsstring *name;
@end
@implementation person
- (instancetype)init{
if (self = [super init]) {
self.name = @"xiaoming";
//注意此__block会复制一份指针出来 一次原始的指针如果置为nil的话,此处复制出来的指针还是野指针
__block __typeof(self)weakself = self;
//__weak __typeof(self)weakself = self;
//__weak person *weakself = self;
void (^block)(void) = ^(void){
//nslog(@"name --> is %@", self.name);
//nslog(@"name --> is %@", weakself.name);
//这样判断会crash 此时weakself为野指针
//weakself 这时候是个野指针。。。野指针也是指针对吧？反正，这个野指针并不为null,虽然它指向的内存并未有什么鸟用，
//然而代码并不知道。所以 执行[weakself dosomething]; 必然闪退。
//注意此__block会复制一份指针出来 一次原始的指针如果置为nil的话,此处复制出来的指针还是野指针
// if (weakself) {
// nslog(@"name --> is %@", weakself.name);
// }
//malloc(22);
// malloc_zon
//这并没有什么卵用。。。weakself 已经是野指针 照样crash
// __strong __typeof(weakself) strongself = weakself;
// if (weakself) {
// nslog(@"name --> is %@", strongself.name);
// }
if (malloc_zone_from_ptr(weakself)) {
nslog(@"name --> is %@", weakself.name);
}
};
for (int i = 0; i < 300; i++) {
// dispatch_async(dispatch_get_global_queue(dispatch_queue_priority_default, 0), ^{
// block();
// });
dispatch_async(dispatch_get_main_queue(), ^{
block();
});
}
}
return self;
}
@end
总结
以上所述是小编给大家介绍的ios mrc 下 block 循环引用问题，希望对大家有所帮助
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