__blockNSArray *array;// 1dispatch_sync(self.concurrentPhotoQueue, ^{// 2 array = [NSArrayarrayWithArray:_photosArray];// 3 });return array; } 这就是你的读函数。按顺序看看编过号的注释,有这些: __block关键字允许对象在 Block 内可变。没有它,array在 Block 内部就只是只读的,你的代码甚...
dispatch_assert(size >=sizeof(struct_os_object_s));return_os_objc_alloc(cls, size); }// 再看一下 _os_objc_allocstaticinlineid _os_objc_alloc(Class cls,size_tsize) { id obj; size -=sizeof(((struct_os_object_s *)NULL)->os_obj_isa);while(unlikely(!(obj = class_createInstanc...
Greatest common divisor, returned as an array of real nonnegative integer values. G is the same size as A and B, and the values in G are always real and nonnegative. G is returned as the same type as A and B. If A and B are of different types, then G is returned as the non...
For the second query, the remaining part of the array will be (2, 9). So answer is 1. For the third query, the remaining part of the array will be (2). So the answer is 2. Solution Approach(1) Brute Force Approach:In this approach, we will calculate the gcd of the array from...
在我们之前的Array的extension上重写load方法,它会同步地返回一个NoteCollection或者抛出一个错误.我们可以重用之前基于DispatchGroup的代码,只需要用信号量来简单地协调该任务即可.1234567891011121314151617181920212223242526272829extension Array where Element: DataSource {...
[webServeraddDefaultHandlerForMethod:@"GET"requestClass:[GCDWebServerRequestclass]processBlock:^GCDWebServerResponse *(GCDWebServerRequest* request) {NSMutableArray* contents = [NSMutableArrayarrayWithObjects:@"\n",@"Hello World!\n",@"\n",nil];//Fake data source we are reading fromGCDWebServe...
sharedPhotoManager->_photosArray = [NSMutableArrayarray]; }returnsharedPhotoManager; } 当前状态下,代码相当简单;你创建了一个单例并初始化一个叫做photosArray的NSMutableArray属性。 然而,if条件分支不是线程安全的;如果你多次调用这个方法,有一个可能性是在某个线程(就叫它线程A)上进入if语句块并可能在shared...
style in Swift, even in Objective-C. That was also the main reason that many developers were avoiding GCD on purpose, and they were choosing the NSOperationQueue. A simple web search about GCD in Swift versions other than the last one will give you a good taste of how GCD syntax had ...
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Swift’sDictionary(andArray) types are value types. When they’re modified, their reference is fully replaced with a new copy of the structure. However, because updating instance variables on Swift objects is not atomic, they arenotthread-safe. Two threads can update a dictionary (for example...