1、NSthread的初始化
1.靜態辦法
- (id)initWithtarget:(id)target selector:(SEL)selector object:(id)argument;
// 初始化線程
NSThread *thread = [[NSThread alloc] initWithtarget:self selector:@selector(run) object:nil];
// 設置線程的優先級(0.0 - 1.0,1.0第一流)
thread.threadPriority = 1;
// 開啟線程
[thread start];
參數解析:
selector :線程履行的辦法,這個selector最多只能吸收一個參數
target :selector新聞發送的對象
argument : 傳給selector的獨一參數,也能夠是nil
2.靜態辦法
+ (void)detachNewThreadSelector:(SEL)selector toTarget:(id)target withObject:(id)argument;
[NSThread detachNewThreadSelector:@selector(run) toTarget:self withObject:nil];
// 挪用終了後,會立時創立並開啟新線程
3.隱式創立線程的辦法
[self performSelectorInBackground:@selector(run) withObject:nil];
2、獲得以後線程
NSThread *current = [NSThread currentThread];
3、獲得主線程
NSThread *main = [NSThread mainThread];
4、暫就緒前哨程
// 暫停2s
[NSThread sleepForTimeInterval:2];
// 或許
NSDate *date = [NSDate dateWithTimeInterval:2 sinceDate:[NSDate date]];
[NSThread sleepUntilDate:date];
5、線程間的通訊
1.在指定線程上履行操作
[self performSelector:@selector(run) onThread:thread withObject:nil waitUntilDone:YES];
2.在主線程上履行操作
[self performSelectorOnMainThread:@selector(run) withObject:nil waitUntilDone:YES];
3.在以後線程履行操作
[self performSelector:@selector(run) withObject:nil];
6、優缺陷
1.長處:NSThread比其他兩種多線程計劃較輕量級,更直不雅地掌握線程對象
2.缺陷:須要本身治理線程的性命周期,線程同步。線程同步對數據的加鎖會有必定的體系開支
7、下載圖片的例子:
新建singeView app
新建項目,並在xib文件上放置一個imageView控件。按住control鍵拖到viewControll
er.h文件中創立imageView IBOutlet
ViewController.m中完成:
//
// ViewController.m
// NSThreadDemo
//
// Created by rongfzh on 12-9-23.
// Copyright (c) 2012年 rongfzh. All rights reserved.
//
#import "ViewController.h"
#define kURL @"http://avatar.csdn.net/2/C/D/1_totogo2010.jpg"
@interface ViewController ()
@end
@implementation ViewController
-(void)downloadImage:(NSString *) url{
NSData *data = [[NSData alloc] initWithContentsOfURL:[NSURL URLWithString:url]];
UIImage *image = [[UIImage alloc]initWithData:data];
if(image == nil){
}else{
[self performSelectorOnMainThread:@selector(updateUI:) withObject:image waitUntilDone:YES];
}
}
-(void)updateUI:(UIImage*) image{
self.imageView.image = image;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// [NSThread detachNewThreadSelector:@selector(downloadImage:) toTarget:self withObject:kURL];
NSThread *thread = [[NSThread alloc]initWithtarget:self selector:@selector(downloadImage:) object:kURL];
[thread start];
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end
線程間通信
線程下載完圖片後怎樣告訴主線程更新界面呢?
[self performSelectorOnMainThread:@selector(updateUI:) withObject:image waitUntilDone:YES];
performSelectorOnMainThread是NSObject的辦法,除可以更新主線程的數據外,還可以更新其他線程的好比:
用: performSelector:onThread:withObject:waitUntilDone:
運轉下載圖片:
圖片下載上去了。
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