ios 块语法的本质

块语法的本质是：函数指针

块语法的回调是通过传递函数指针实现的。

贴图贴码为快：

主函数：

#import <Foundation/Foundation.h>
#import "HomeClass.h"

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        HomeClass *home = [[HomeClass alloc] init];
        [home method];
        
    }
    return 0;
}

HomeClass类：

#import <Foundation/Foundation.h>

@interface HomeClass : NSObject

- (void)method;

- (void)aactin:(NSString *)string;

@end

//
//  HomeClass.m
//  BlockDemo
//
//  Created by hanjun on 13-3-14.
//  Copyright (c) 2013年 CompanyOfHanJun. All rights reserved.
//

#import "HomeClass.h"
#import "ToolClass.h"

@implementation HomeClass

- (void)aactin:(NSString *)string{
    NSLog(@"%@",string);
}

- (void)method{
    ToolClass *tool = [[ToolClass alloc] init];

    [tool handleData:0 numberb:0 Function:^(int a, int b) {
        NSLog(@"%d %d",a,b);
    }];
    
    [tool action:^NSString *(NSString * string) {
        NSLog(@"callBack:%@",string);
        return @"hanjun";
    }];
        
}



@end

ToolClass类

#import <Foundation/Foundation.h>

@interface ToolClass : NSObject
-(void)handleData:(int)a numberb:(int)b Function:(void (^)(int a,int b))testFunction;

- (void)presentViewCompletion:(void (^)(void))completion;

- (void)action:(NSString *(^)(NSString *))string;
- (void)aactin:(NSString *)string;
@end

//
//  ToolClass.m
//  BlockDemo
//
//  Created by hanjun on 13-3-14.
//  Copyright (c) 2013年 CompanyOfHanJun. All rights reserved.
//

#import "ToolClass.h"

@implementation ToolClass

//块值传参，没有返回值
-(void)handleData:(int)a numberb:(int)b Function:(void (^)(int a,int b))testFunction
{
    int aaa=5,bbb=10;
    
    testFunction(aaa,bbb);
}

//块不仅可以传参，还可以有返回值
- (void)action:(NSString *(^)(NSString *))string
{
    
    NSString * backReturn = string(@"yhy");
    NSLog(@"backReturn = %@",backReturn);
}


int (^oneFrom)(int) = ^(int anInt)
{
    return anInt-1;
};

int (^completion)(int)=^(int a){
    return a;
};

//int (^completion)(int)=^(int a1){
//    return a1+5;
//};

int (^myBlock)(int)=^(int a1){
    return a1;
};

@end