抽时间看了下BlocksKit的部分代码, 了解了下内部实现, 总结一下.
数组:
初始化数组:
NSArray *arr = @[@"1a", @"2a", @"3a", @"4a"];
分析每个方法:
1.bk_each -> 断言判断下block, 对数组快速遍历(枚举);
[arr bk_each:^(id obj) {
NSLog(@"%@", obj);
}];
内部实现:
- (void)bk_each:(void (^)(id obj))block
{
NSParameterAssert(block != nil);
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
block(obj);
}];
}
打印结果:
2016-03-15 15:58:59.469 TBlockskit[8744:193322] 1a
2016-03-15 15:58:59.470 TBlockskit[8744:193322] 2a
2016-03-15 15:58:59.470 TBlockskit[8744:193322] 3a
2016-03-15 15:58:59.470 TBlockskit[8744:193322] 4a
2.bk_apply -> 也是枚举, 提供了两种枚举类型: NSEnumerationConcurrent 并发, 完成顺序是不确定的; NSEnumerationReverse 以反序方式枚举.
- (void)bk_apply:(void (^)(id obj))block
{
NSParameterAssert(block != nil);
[self enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
block(obj);
}];
}
3.bk_match -> 根据obj参数加上自己的筛选条件(此处没有用到参数), return YES会记录当前元素的下表, 然后根据self[index]返回对应的对象
id obj = [arr bk_match:^BOOL(id obj) {
return arc4random() % 2 ? YES: NO;
}];
NSLog(@"--%@", obj);
内部实现:
- (id)bk_match:(BOOL (^)(id obj))block
{
NSParameterAssert(block != nil);
NSUInteger index = [self indexOfObjectPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
return block(obj); //若 block(obj) 一直为 NO, 该数组会全部遍历之后才走下面判断
}];
if (index == NSNotFound)
return nil;
return self[index];
}
4.bk_select -> 调用了objectsAtIndexes方法, 以数组形式返回了所有判断之后return YES的数据
NSArray *select = [arr bk_select:^BOOL(id obj) {
return arc4random() % 2? YES: NO;
}];
NSLog(@"select: %@", select);
2016-03-15 16:54:20.452 TBlockskit[9043:232123] select: (
2a,
4a
)
内部实现:
- (NSArray *)bk_select:(BOOL (^)(id obj))block
{
NSParameterAssert(block != nil);
return [self objectsAtIndexes:[self indexesOfObjectsPassingTest:^BOOL(id obj, NSUInteger idx, BOOL *stop) {
return block(obj);
}]];
}
5.bk_reject -> 跟bk_select刚好相反, 以数组形式返回了所有判断之后return NO的数据
NSArray *reject = [arr bk_reject:^BOOL(id obj) {
return NO;
}];
2016-03-15 16:54:20.452 TBlockskit[9043:232123] reject: (
1a,
2a,
3a,
4a
)
内部实现:
- (NSArray *)bk_reject:(BOOL (^)(id obj))block
{
NSParameterAssert(block != nil);
return [self bk_select:^BOOL(id obj) {
return !block(obj);
}];
}
6.bk_map -> 枚举数组, 对数组对象进行操作, 若操作之后为nil就创建NSNull对象替代, 返回数组
//例如拼上.png后缀
NSArray *new = [arr bk_map:^id(id obj) {
return [obj stringByAppendingString:@".png"];
}];
//源码
- (NSArray *)bk_map:(id (^)(id obj))block
{
NSParameterAssert(block != nil);
NSMutableArray *result = [NSMutableArray arrayWithCapacity:self.count];
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
id value = block(obj) ?: [NSNull null];
[result addObject:value];
}];
return result;
}
7.bk_reduce:withBlock: -> 对数组中对象进行指定操作, initial为初始数据, sum 为初始数据与每个对象操作之后的结果(initial要保护,防止为空), 例如拼接为字符串或者求和
NSString *concentrated = [arr bk_reduce:@"_" withBlock:^id(id sum, id obj) {
return [sum stringByAppendingString:obj];
}];
- (id)bk_reduce:(id)initial withBlock:(id (^)(id sum, id obj))block
{
NSParameterAssert(block != nil);
__block id result = initial;
//赋给result初始值, 再与数组中元素进行操作
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
result = block(result, obj);
}];
return result;
}
8.bk_reduceInteger:(NSInteger)initial withBlock: 与 bk_reduceFloat:(CGFloat)inital withBlock: 跟7方法相似, 只是操作的为NSInteger或CGFloat类型的
9.bk_any:与bk_none:都调用了bk_match:方法
//数组中有一个满足条件就返回YES
- (BOOL)bk_any:(BOOL (^)(id obj))block
{
return [self bk_match:block] != nil;
}
//数组中都不满足条件就返回YES
- (BOOL)bk_none:(BOOL (^)(id obj))block
{
return [self bk_match:block] == nil;
}
//数组中都满足条件就返回YES
- (BOOL)bk_all:(BOOL (^)(id obj))block
{
NSParameterAssert(block != nil);
__block BOOL result = YES;
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
if (!block(obj)) {
//数组中有一个不满足条件就返回 NO
result = NO;
*stop = YES;
}
}];
return result;
}
10.bk_corresponds:(NSArray *)list withBlock: -> 判断调用的数组与list是否相等, 判断条件外部指定(判断地址,内容,或转化之后的数据),例如以下判断:
NSArray *numbers = @[ @(1), @(2), @(3) ];
NSArray *letters = @[ @"1", @"2", @"3" ];
BOOL doesCorrespond = [numbers bk_corresponds:letters withBlock:^(id number, id letter) {
return [[number stringValue] isEqualToString:letter];
}];
源码:
- (BOOL)bk_corresponds:(NSArray *)list withBlock:(BOOL (^)(id obj1, id obj2))block
{
NSParameterAssert(block != nil);
__block BOOL result = NO;
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
//貌似要求当前数组长度要小于list长度...短了也相等, 醉了
if (idx < list.count) {
id obj2 = list[idx];
result = block(obj, obj2);
} else {
result = NO;
}
*stop = !result;
}];
return result;
}
看了下 NSDictionary、NSIndexSet、NSSet、NSOrderedSet 都是这样的用法, 就不一一累述~~先搞这些吧
03-16-续集
可变数组:
1.根据条件移除数组中的元素
NSMutableArray *mArr = [@[@"a", @"b", @"c", @"d"] mutableCopy];
//保留满足条件(return YES)的对象, 不满足移除;
[mArr bk_performSelect:^BOOL(id obj) {
return [mArr indexOfObject:obj] % 2;
}];
//留下[b,d];
NSLog(@"return YES: %@", mArr);
//移除满足条件(return YES)的对象, 不满足保留;
[mArr bk_performReject:^BOOL(id obj) {
return [mArr indexOfObject:obj] % 2;
}];
//留下[b];
NSLog(@"return NO: %@", mArr);
2.对数组相应对象的处理
NSMutableArray *mArr1 = [@[@"a", @"b", @"c.png", @"d.png"] mutableCopy];
[mArr1 bk_performMap:^id(id obj) {
//没有以.png结尾的拼接上.png
return [obj hasSuffix:@".png"] ? obj :[obj stringByAppendingString:@".png"];
}];
NSLog(@"bk_performMap: %@", mArr1);
//打印结果:
2016-03-16 17:32:32.135 TBlockskit[1951:49505] bk_performMap: (
"a.png",
"b.png",
"c.png",
"d.png"
)
源码:
- (void)bk_performMap:(id (^)(id obj))block {
NSParameterAssert(block != nil);
NSMutableArray *new = [self mutableCopy];
[self enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
//外部处理为空的创建NSNull对象
id value = block(obj) ?: [NSNull null];
//处理之后与原obj相同的不变,
if ([value isEqual:obj]) return;
//不相同的用新对象替换老的
new[idx] = value;
}];
//把数组用new替代
[self setArray:new];
}
然而.NSDictionary、NSIndexSet、NSSet、NSOrderedSet 也都是这样的用法