iOS Development--Multithreading OC & (iv) thread communication

Inter-thread communication

A simple explanation

Inter-thread communication: In 1 processes, threads often do not exist in isolation, and frequent communication between multiple threads is required

The embodiment of inter-thread communication

1 Threads pass data to another 1 threads

After performing a specific task in 1 threads, go to another 1 thread to continue the task

Common methods for inter-thread communication

-(void) Performselectoronmainthread: (SEL) Aselector withobject: (ID) arg waituntildone: (BOOL) wait;

-(void) Performselector: (SEL) aselector onthread: (Nsthread *) THR Withobject: (ID) arg waituntildone: (BOOL) wait;

Example of inter-thread communication – image download

Code Listing 1:

1 //2 //YYVIEWCONTROLLER.M3 //06-nsthread04-inter-thread communication4 //5 //Created by Apple on 14-6-23.6 //Copyright (c) 2014 itcase. All rights reserved.7 //8 9 #import "YYViewController.h"Ten @interfaceYyviewcontroller () One@property (Weak, nonatomic) Iboutlet Uiimageview *IconView; A @end -  - @implementationYyviewcontroller the  -- (void) Viewdidload - { - [Super Viewdidload]; + } -  +-(void) Touchesbegan: (Nsset *) touches withevent: (Uievent *)Event A { at  - //call the download method in a child thread to download the picture - [Self performselectorinbackground: @selector (download) Withobject:nil]; - } -  -   in  --(void) Download to { +     //1. Download the picture according to the URL -     //download pictures from the network theNsurl *urlstr=[nsurl urlwithstring:@"FDSF"]; *  $     //convert a picture to binary dataPanax NotoginsengNSData *data=[nsdata DATAWITHCONTENTSOFURL:URLSTR];//This line of work can be time-consuming -  the     //convert the data into pictures +UIImage *image=[UIImage Imagewithdata:data]; A   the     //2. Go back to the main thread to set the picture + [Self performselectoronmainthread: @selector (settingimage:) withobject:image Waituntildone:no]; - } $  $   -  - //set the display picture the-(void) Settingimage: (UIImage *) Image - {WuyiSelf.iconview.image=image; the } -  Wu @end

Code Listing 2:

1 //2 //YYVIEWCONTROLLER.M3 //06-nsthread04-inter-thread communication4 //5 //Created by Apple on 14-6-23.6 //Copyright (c) 2014 itcase. All rights reserved.7 //8 9 #import "YYViewController.h"Ten #import<NSData.h> One  A @interfaceYyviewcontroller () -@property (Weak, nonatomic) Iboutlet Uiimageview *IconView; - @end the  - @implementationYyviewcontroller -  -- (void) Viewdidload + { - [Super Viewdidload]; + } A  at   --(void) Touchesbegan: (Nsset *) touches withevent: (Uievent *)Event - { - //call the download method in a child thread to download the picture -  - [Self performselectorinbackground: @selector (download) Withobject:nil]; in } -  to   +-(void) Download - { the  *     //1. Download the picture according to the URL $     //download pictures from the networkPanax NotoginsengNsurl *urlstr=[nsurl urlwithstring:@"FDSF"]; -  the     //convert a picture to binary data +NSData *data=[nsdata DATAWITHCONTENTSOFURL:URLSTR];//This line of work can be time-consuming A  the     //convert the data into pictures +UIImage *image=[UIImage Imagewithdata:data]; -  $     //2. Go back to the main thread to set the picture $     //The first way - //[Self performselectoronmainthread: @selector (settingimage:) withobject:image Waituntildone:no]; -  the     //The second way -     //[Self.imageview performselector: @selector (setimage:) onthread:[nsthread Mainthread] Withobject:image Waituntildone:no];Wuyi  the     //The Third Way - [Self.iconview performselectoronmainthread: @selector (setimage:) withobject:image Waituntildone:no]; Wu } -  About  $ //set the display picture - //-(void) Settingimage: (UIImage *) Image - //{ - //Self.iconview.image=image; A //} +  the @end

iOS Development--Multithreading OC & (iv) thread communication