新型的遍历,用block + stop + obj

/**

 *  新型 for 循环遍历

 */

typedef void (^MJClassesBlock)(Class c,BOOL *stop);

- (void)enumerateClassesWithBlock:(MJClassesBlock)block

{

    // 1.没有block就直接返回

    if (block == nil)return;

    

    // 2.停止遍历的标记

    BOOL stop
4000
= NO;

    

    // 3.当前正在遍历的类

    Class c = [self
class];

    

    // 4.开始遍历每一个类

    while (c && !stop) {

        // 4.1.执行操作

        block(c, &stop);

        

        // 4.2.获得父类

        c = class_getSuperclass(c);

    }

}

// 数组遍历

typedef void (^MJClassesBlock)(id obj, NSInteger index, BOOL *stop);

@implementation ViewController

- (void)viewDidLoad {

    [superviewDidLoad];

    // Do any additional setup after loading the view, typically from a nib.

    

    NSArray * arr =@[
@"01",@"12",
@"23",@"34",
@"45",@"56",
@"67",@"78",
@"89",@"90"];

    [self enumerateClassesWithBlock:^(NSString *  obj,NSInteger index,
BOOL *stop) {

        NSLog(@"%@===%ld==%d", obj, (long)index, *stop);

        if (index ==
6) {

            *stop = YES;

        }

    } withArr:arr];

   

}

-(void)enumerateClassesWithBlock:(MJClassesBlock)block withArr:(NSArray *)arr{

    if (block == nil)return;

    BOOL stop = NO;

    

    for (NSInteger i =0; i < arr.count; i++) {

        id obj = arr[i];

        block(obj, i, &stop);

        if (stop ==
YES)  break;

    }

}

// 打印结果

2016-03-29 11:14:33.206 magic[987:63592] 01===0==0

2016-03-29 11:14:33.206 magic[987:63592] 12===1==0

2016-03-29 11:14:33.207 magic[987:63592] 23===2==0

2016-03-29 11:14:33.207 magic[987:63592] 34===3==0

2016-03-29 11:14:33.207 magic[987:63592] 45===4==0

2016-03-29 11:14:33.208 magic[987:63592] 56===5==0

2016-03-29 11:14:33.208 magic[987:63592] 67===6==0

#pragma mark 利用迭代器

void arrayFor4(){

    NSArray *array = [NSArray arrayWithObjects:@"1",@"2",@"3",nil];

    NSEnumerator *enumerator = [array objectEnumerator];

    //如果放到遍历之后，则取到空，原因是，遍历完了，就没值了

    NSArray *array2 = [enumerator allObjects];

    NSLog(@"array2:%@", array2);

   

    //获取下一个需要遍历的元素

    id obj = nil;

    while (obj = [enumerator nextObject]) {

        NSLog(@"obj=%@", obj);

    }

}