iOS Development multithreading

<span id="Label3"></p><p><p><span style="font-size: 16px;">-(void) Viewdidload {</span></p></p><p><p><span style="font-size: 16px;">[super viewdidload];</span></p></p><p><p><span style="font-size: 16px;">/* process: Running Program thread: the basic execution unit of a process, where the task is executed</span></p></p><p><p><span style="font-size: 16px;">Thread Serial: 1 threads in the execution of a task serially, at the same time, 1 threads can only perform one task</span></p></p><p><p><span style="font-size: 16px;">Multithreading: multiple threads can be opened in a process, the principle is that the CPU is quickly dispatched between multiple threads (switching), more CPU</span></p></p><p><p><span style="font-size: 16px;">Main Thread/ui threads: display/refresh/process ui, Place time-consuming processing on child threads */</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">/* Create Thread</span></p></p><p><p><span style="font-size: 16px;">To manually start a thread: [thread start] then the task is Executed.</span></p></p><p><p><span style="font-size: 16px;">Nsthread *thread = [[nsthread alloc]initwithtarget:self selector: @selector (text) object:nil];</span></p></p><p><p><span style="font-size: 16px;">To start a thread automatically:</span></p></p><p><p><span style="font-size: 16px;">[nsthread detachnewthreadselector: @selector (text) totarget:withobiect:]</span></p></p><p><p><span style="font-size: 16px;">Implicitly created and Started:</span></p></p><p><p><span style="font-size: 16px;">[self performselectorinbackground: @selector (text) withobject:]</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">Get the main thread</span></p></p><p><p><span style="font-size: 16px;">Nsthread *mainthread = [nsthread mainthread];</span></p></p><p><p><span style="font-size: 16px;">Determine if the main thread</span></p></p><p><p><span style="font-size: 16px;">BOOL *b = [mainthread ismainthread];</span></p></p><p><p><span style="font-size: 16px;">Gets the current thread</span></p></p><p><p><span style="font-size: 16px;">Nsthread *currentthread = [nsthread currentthread];</span></p></p><p><p><span style="font-size: 16px;">Priority of Thread scheduling</span></p></p><p><p><span style="font-size: 16px;">+ (double) threadpriority;</span></p></p><p><p><span style="font-size: 16px;">+ (BOOL) setthreadpriority: (double) p;</span></p></p><p><p><span style="font-size: 16px;">Set the name of the thread</span></p></p><p><p><span style="font-size: 16px;">-(void) setName: (nsstring *) n;</span></p></p><p><p><span style="font-size: 16px;">-(nsstring *) name;</span></p></p><p><p><span style="font-size: 16px;">Exit Thread: +exit</span></p></p><p><p><span style="font-size: 16px;">*/</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">/* thread safety: A resource may be accessed by multiple threads, causing data confusion and data security issues</span></p></p><p><p><span style="font-size: 16px;">Fix: thread synchronization technology, mutex @synchronized (lock Object) {//code required to lock}</span></p></p><p><p><span style="font-size: 16px;">Only one thread can access a time period until the thread is finished</span></p></p><p><p><span style="font-size: 16px;">Atomic: Atomic properties, linear security, locking for setter methods</span></p></p><p><p><span style="font-size: 16px;">*/</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">/* communication between threads: transferring data between lines, passing tasks</span></p></p><p><p><span style="font-size: 16px;">-(void) performSelectorOnMainThread:withObject:waitUntilDone:</span></p></p><p><p><span style="font-size: 16px;">-(void) performSelector:onThread:withObiect:waitUntilDone:</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">*/</span></p></p><p><p><span style="font-size: 16px;">/* thread blockage (call The sleep method or a synchronous lock, at which point the thread cannot be dispatched):</span></p></p><p><p><span style="font-size: 16px;">The first kind [nsthread sleepfortimeinterval:2.0];</span></p></p><p><p><span style="font-size: 16px;">The second is based on the current time as a benchmark nsdate *date = [nsdate datewithtimeintervalsincenow:4.0];</span></p></p><p><p><span style="font-size: 16px;">[nsthread sleepuntildate:date];</span></p></p><p><p><span style="font-size: 16px;">Thread Death: An exception was forced to quit when the task ended</span></p></p><p><p><span style="font-size: 16px;">The thread is created, but the thread does not open immediately!!!!</span></p></p><p><p><span style="font-size: 16px;">*/</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">}</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p><span style="font-size: 16px;">-(void) didreceivememorywarning {</span></p></p><p><p><span style="font-size: 16px;">[super didreceivememorywarning];</span></p></p><p><p><span style="font-size: 16px;">Dispose of any resources the can be Recreated.</span></p></p><p><p><span style="font-size: 16px;">}</span></p></p><p><p><span style="font-size: 16px;">-(void) touchesbegan: (nsset *) touches withevent: (uievent *) Event</span></p></p><p><p><span style="font-size: 16px;">{</span></p></p><p><p><span style="font-size: 16px;">[self performselectorinbackground: @selector (download) withobject:nil];</span></p></p><p><p><span style="font-size: 16px;">}</span></p></p><p><p><span style="font-size: 16px;">-(void) Download</span></p></p><p><p><span style="font-size: 16px;">{//get a picture</span></p></p><p><p><span style="font-size: 16px;">NSString *imagestrring = [nsstring stringwithformat:@ "http://i6.topit.me/6/5d/45/1131907198420455d6o.jpg"];</span></p></p><p><p><span style="font-size: 16px;">Nsurl *imageurl = [nsurl urlwithstring:imagestrring];</span></p></p><p><p><span style="font-size: 16px;">NSData *imagedata = [nsdata datawithcontentsofurl:imageurl];</span></p></p><p><p><span style="font-size: 16px;">UIImage *image = [UIImage imagewithdata:imagedata];</span></p></p><p><p><span style="font-size: 16px;">Return main thread The second is the parameter to be passed to this method</span></p></p><p><p><span style="font-size: 16px;">[self performselectoronmainthread: @selector (settingimage:) withobject:image waituntildone:no];</span></p></p><p><p><span style="font-size: 16px;">}</span></p></p><p><p><span style="font-size: 16px;">-(void) settingimage: (UIImage *) image</span></p></p><p><p><span style="font-size: 16px;">{</span></p></p><p><p><span style="font-size: 16px;">Self.imageView.image = image;</span></p></p><p><p><span style="font-size: 16px;">}</span></p></p><p><p><span style="font-size: 16px;">//</span></p></p><p><p><span style="font-size: 16px;">-(ibaction) buttonclicked: (id) Sender {</span></p></p><p><p><span style="font-size: 16px;">Nsthread *currentthread = [nsthread currentthread];</span></p></p><p><p><span style="font-size: 16px;">NSLog (@ "currentthread----%@", currentthread);</span></p></p><p><p><span style="font-size: 16px;">Nsthread *mainthread = [nsthread mainthread];</span></p></p><p><p><span style="font-size: 16px;">NSLog (@ "mainthread-----%@", mainthread);</span></p></p><p><p><span style="font-size: 16px;">[self creatnewthread];</span></p></p><p><p><span style="font-size: 16px;">//</span></p></p><p><p><span style="font-size: 16px;">//}</span></p></p><p><p><span style="font-size: 16px;">-(void) Creatnewthread</span></p></p><p><p><span style="font-size: 16px;">//{</span></p></p><p><p><span style="font-size: 16px;">Nsthread *newthread = [[nsthread alloc]initwithtarget:self selector: @selector (run) object:nil];</span></p></p><p><p><span style="font-size: 16px;">Newthread.name = @ "thread a";</span></p></p><p><p><span style="font-size: 16px;">[newthread start];</span></p></p><p><p><span style="font-size: 16px;">//}</span></p></p><p><p><span style="font-size: 16px;">-(void) Run</span></p></p><p><p><span style="font-size: 16px;">{nsthread *current = [nsthread currentthread];</span></p></p><p><p><span style="font-size: 16px;">For (int i=0; i<100; I++) {</span></p></p><p><p><span style="font-size: 16px;">NSLog (@ "run---%@", current);</span></p></p><p><p><span style="font-size: 16px;">//    }</span></p></p><p><p><span style="font-size: 16px;">//}</span></p></p><p><p><span style="font-size: 16px;"></span></p></p><p><p>iOS Development multithreading</p></p></span>