一、創(chuàng)建多線程的五種方式
1.開(kāi)啟線程的方法一
NSThread * thread=[[NSThread alloc] initWithTarget:self selector:@selector(_update) object:nil];
2.開(kāi)啟線程的方法二
[NSThread detachNewThreadSelector:@selector(_update) toTarget:self withObject:nil];
3.開(kāi)啟線程的方法三
[self performSelectorInBackground:@selector(_update) withObject:nil];
4.開(kāi)啟線程的方法四
NSOperationQueue *queue=[[NSOperationQueue alloc] init];
[queue addOperationWithBlock:^{
for(int i=0;i<50;i++){
printf("子線程 ");
}
}];
5.開(kāi)啟線程的方法五
//第一步開(kāi)啟線程池
NSOperationQueue * queue=[[NSOperationQueue alloc] init];
//設(shè)置并發(fā)數(shù)目
[queue setMaxConcurrentOperationCount:2];
//第二部創(chuàng)建多線程添加到線程池
NSInvocationOperation * thread1=[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(_update1) object:nil];
NSInvocationOperation *thread2=[[NSInvocationOperation alloc] initWithTarget:self selector:@selector(_update2) object:nil];
[thread1 setQueuePriority:NSOperationQueuePriorityVeryLow];
[thread2 setQueuePriority:NSOperationQueuePriorityVeryHigh];
[queue addOperation:thread1];
[queue addOperation:thread2];
二、多線程應(yīng)用實(shí)例，加載圖片。
1.核心思想
考慮到如果加載網(wǎng)絡(luò)圖片會(huì)延遲，在一個(gè)主線程加載會(huì)影響控件的渲染，此時(shí)可以采取多線程，異步加載完成后刷新UI。
2.實(shí)現(xiàn)思路
通過(guò)為UIImageView 增加類目來(lái)實(shí)現(xiàn)多線程下載。
主要代碼：
#import "UIImageView+thread.h"
@implementation UIImageView(load)
- (void) setImageWithUrl:(NSString *)url{
[self performSelectorInBackground:@selector(_loadImage:) withObject:url];
}
- (void) _loadImage:(NSString *)u{
@autoreleasepool {
NSURL *url=[NSURL URLWithString:u];
NSData *data=[NSData dataWithContentsOfURL:url];
UIImage *image=[UIImage imageWithData:data];
[self performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:NO];
}
}