着重说一下 block 的应用场景，为什么大家都愿意用 block :
- 直观，简洁，可以方便的在一个场景里面使用，并可以捕获当前的变量。
//case 1可以声明不同语义
//.h
typedef void(^CompletesBlock)(int status);
typedef void(^ErrorBlock)(int status);
typedef void(^FailedBlock)(int status);
typedef void(^ProgressBlock)(int status);
- (void)doSomething:(CompletesBlock)completeBlock failed:(FailedBlock)failedBlock;
//.m
- (void)doSomething:(CompletesBlock)completeBlock failed:(FailedBlock)failedBlock {
if (completeBlock){
completeBlock(1);
completeBlock = nil;
}
if (failedBlock) {
failedBlock(0);
failedBlock = nil;
}
}
//调用
BlockHandler *handler = [BlockHandler new];
//case 1
[handler doSomething:^(int status) {
NSLog(@"handler success %@", @(status));
}failed:^(int status) {
NSLog(@"handler failed %@", @(status));
}];
//case 2
handler.completeBlock = ^(int status) {
NSLog(@"handler success 2");
};
handler.failedBlock = ^(int status) {
NSLog(@"handler failed 2");
};
[handler innerDoSomething];
- 可以指定调用的Queue
//.m
- (void)addBlock:(NSOperationQueue *)queue block:(void (^)(int))block {
[queue addOperationWithBlock:^{
if (block) {
block(1);
}
}];
}
//调用
NSOperationQueue *queue = [NSOperationQueue mainQueue];
[handler addBlock:queue block:^(int i) {
NSLog(@"add block on queue %@", @(i));
}];
