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ios学习笔记block回调的应用（一个简单的例子）
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一、什么是Blocks ?二、在ios開發中，什么情況下使用Block ?代碼片段的封裝，適用作工作單元，通常用來做并發任務、遍歷、以及回調。?三、block如何申明（對比于c語言中的函數申明） ?
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四、c函數指正和blocks調用 ?五、__block? 關鍵字 ?六、block的幾個小例子 ?
Java代碼??
#import?<Cocoa/Cocoa.h>?? ?? ?? int?main(int?argc,?char?*argv[])?? {?? ????@autoreleasepool?{?? ????????NSLog(@"Hello?world");?? ????????void?(^myblocks)?(void)?=?NULL;?? ????????myblocks?=?^(void)?{?? ????????????NSLog(@"in?blocks");?? ????????};?? ????????NSLog(@"before?myblocks");?? ????????myblocks();?? ????????NSLog(@"after?myblocks");?? ?????????? ?????????? ????????int?(^myblocks2)?(int?a,?int?b)?=?^(int?a,?int?b)?{?? ????????????int?c?=?a?+?b;?? ????????????return?c;?? ????????};?? ????????NSLog(@"before?blocks2");?? ????????int?ret?=?myblocks2(10,?20);?? ????????NSLog(@"after?blocks2?ret?%d",?ret);?? ?????????? ???????? ????????__blockint?sum?=?0;?? ????????int?(^myblocks3)?(int?a,?int?b)?=?^(int?a,?int?b)?{?? ????????????sum?=?a?+?b;?? ????????????return3;?? ????????};?? ????????myblocks3(20,?30);?? ????????NSLog(@"sum?is?%d",?sum);?? ????}?? ????returnNSApplicationMain(argc,?(constchar?**)argv);?? }?? 七、block寫的回調例子 ?
Java代碼??
#import?<Foundation/Foundation.h>?? ?? ?? @interface?Dog?:?NSObject?{?? ????int?_ID;?? ????NSTimer?*timer;?? ????int?barkCount;?? ?????? ???? ????void?(^BarkCallback)?(Dog?*thisDog,?int?count);?? }?? @property?(assign)?int?ID;?? ?? ?? -(void)?setBark:(?void?(^)?(Dog?*thisDog,?int?count)?)?eachBark;?? ?? ?? @end??
Java代碼??
#import?"Dog.h"?? ?? ?? @implementation?Dog?? @synthesize?ID?=?_ID;?? ?? ?? -(id)?init?? {?? ????self?=?[superinit];?? ????if?(self)?{?? ???????? ????????timer?=?[NSTimerscheduledTimerWithTimeInterval:1.0ftarget:selfselector:@selector(updateTimer:)?userInfo:nilrepeats:YES];?? ?????????? ????}?? ????returnself;?? }?? ?? ?? -(void)?updateTimer:(id)?arg?? {?? ????barkCount?++;?? ????NSLog(@"dog?%d?bark?count?%d",?_ID,?barkCount);?? ???? ????if?(BarkCallback)?{?? ???????? ????????BarkCallback(self,?barkCount);?? ????}?? }?? ?? ?? ?? ?? -(void)?setBark:(void?(^)(Dog?*,?int))eachBark?? {?? ????[BarkCallbackrelease];?? ????BarkCallback?=?[eachBark?copy];?? }?? ?? ?? -(void)?dealloc?? {?? ????[BarkCallbackrelease];?? ????[superdealloc];?? }?? @end??
Java代碼??
#import?<Foundation/Foundation.h>?? #import?"Dog.h"?? ?? ?? @interface?Person?:?NSObject?? {?? ????Dog?*_dog;?? }?? ?? ?? @property?(retain)?Dog?*dog;?? ?? ?? @end??
Java代碼??
#import?"Person.h"?? ?? ?? @implementation?Person?? @synthesize?dog?=?_dog;?? ?? ?? -(void)?setDog:(Dog?*)dog?? {?? ????if?(_dog?!=?dog)?{?? ????????[_dogrelease];?? ????????_dog?=?[dog?retain];?? ?????????? ????????[_dogsetBark:^(Dog?*thisDog,?int?count)?{?? ????????????NSLog(@"person?dog?%d?count?%d",?[thisDog?ID],?count);?? ????????}];?? ????}?? }?? ?? ?? -(Dog?*)?dog?? {?? ????return_dog;?? }?? ?? ?? -(void)?dealloc?? {?? ????self.dog?=?nil;?? ????[superdealloc];?? }?? ?? ?? @end??
Java代碼??
#import?<Foundation/Foundation.h>?? #import?"Person.h"?? #import?"Dog.h"?? ?? ?? int?main(int?argc,?constchar?*?argv[])?? {??
轉載于:https://www.cnblogs.com/kenshinobiy/p/4814982.html
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