iOS 如何在cell上面毫无卡顿的同时加载大量高清图片

释放双眼,带上耳机,听听看~!
//
//  ViewController.m
//  加载高清大图
//
//  Created by H on 
//  Copyright © 年 H. All rights reserved.
//
#import "ViewController.h"
//定义一个block
typedef BOOL(^RunloopBlock)(void);
static NSString *IDENTIFIER = @"IDENTIFIER";
static CGFloat CELL_HEIGHT = 135.f;
@interface ViewController ()<UITableViewDataSource, UITableViewDelegate>
/** 存放任务的数组  */
@property(nonatomic,strong)NSMutableArray * tasks;
/** 任务标记  */
@property(nonatomic,strong)NSMutableArray * tasksKeys;
/** 最大任务数 */
@property(assign,nonatomic)NSUInteger max;
/** timer  */
@property(nonatomic,strong)NSTimer * timer;
@property (nonatomic, strong) UITableView *exampleTableView;
@end
@implementation ViewController
-(void)_timerFiredMethod{
}
- (void)viewDidLoad {
[super viewDidLoad];
_max = 18;
_tasks = [NSMutableArray array];
_tasksKeys = [NSMutableArray array];
_timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(_timerFiredMethod) userInfo:nil repeats:YES];
//注册Cell
[self.exampleTableView registerClass:[UITableViewCell class] forCellReuseIdentifier:IDENTIFIER];
//注册监听
[self addRunloopObserver];
}
//MARK: 内部实现方法
//加载第一张
+(void)addImage1With:(UITableViewCell *)cell{
//第一张
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(5, 20, 85, 85)];
imageView.tag = 1;
NSString *path1 = [[NSBundle mainBundle] pathForResource:@"spaceship" ofType:@"png"];
UIImage *image = [UIImage imageWithContentsOfFile:path1];
imageView.contentMode = UIViewContentModeScaleAspectFit;
imageView.image = image;
[UIView transitionWithView:cell.contentView duration:0.3 options:(UIViewAnimationOptionCurveEaseInOut | UIViewAnimationOptionTransitionCrossDissolve) animations:^{
[cell.contentView addSubview:imageView];
} completion:nil];
}
//加载第二张
+(void)addImage2With:(UITableViewCell *)cell{
//第二张
UIImageView *imageView1 = [[UIImageView alloc] initWithFrame:CGRectMake(105, 20, 85, 85)];
imageView1.tag = 2;
NSString *path1 = [[NSBundle mainBundle] pathForResource:@"spaceship" ofType:@"png"];
UIImage *image1 = [UIImage imageWithContentsOfFile:path1];
imageView1.contentMode = UIViewContentModeScaleAspectFit;
imageView1.image = image1;
[UIView transitionWithView:cell.contentView duration:0.3 options:(UIViewAnimationOptionCurveEaseInOut | UIViewAnimationOptionTransitionCrossDissolve) animations:^{
[cell.contentView addSubview:imageView1];
} completion:nil];
}
//加载第三张
+(void)addImage3With:(UITableViewCell *)cell{
//第三张
UIImageView *imageView2 = [[UIImageView alloc] initWithFrame:CGRectMake(200, 20, 85, 85)];
imageView2.tag = 3;
NSString *path1 = [[NSBundle mainBundle] pathForResource:@"spaceship" ofType:@"png"];
UIImage *image2 = [UIImage imageWithContentsOfFile:path1];
imageView2.contentMode = UIViewContentModeScaleAspectFit;
imageView2.image = image2;
[UIView transitionWithView:cell.contentView duration:0.3 options:(UIViewAnimationOptionCurveEaseInOut | UIViewAnimationOptionTransitionCrossDissolve) animations:^{
[cell.contentView addSubview:imageView2];
} completion:nil];
}
//MARK:  UI初始化方法
//设置tableview大小
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
self.exampleTableView.frame = self.view.bounds;
}
//Cell 高度
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
return CELL_HEIGHT;
}
//加载tableview
- (void)loadView {
self.view = [UIView new];
self.exampleTableView = [UITableView new];
self.exampleTableView.delegate = self;
self.exampleTableView.dataSource = self;
[self.view addSubview:self.exampleTableView];
}
#pragma mark - <tableview>
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
return 399;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:IDENTIFIER];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
//干掉contentView上面的子控件!! 节约内存!!
for (NSInteger i = 1; i <= 3; i++) {
//干掉contentView 上面的所有子控件!!
[[cell.contentView viewWithTag:i] removeFromSuperview];
}
//不要直接加载图片!! 你将加载图片的代码!都给RunLoop!!
[self addTask:^BOOL{
[ViewController addImage1With:cell];
return YES;
} withKey:indexPath];
[self addTask:^BOOL{
[ViewController addImage2With:cell];
return YES;
} withKey:indexPath];
[self addTask:^BOOL{
[ViewController addImage3With:cell];
return YES;
} withKey:indexPath];
return cell;
}
#pragma mark - <RunLoop>
//MARK: 添加任务
-(void)addTask:(RunloopBlock)unit withKey:(id)key{
[self.tasks addObject:unit];
[self.tasksKeys addObject:key];
//保证之前没有显示出来的任务,不再浪费时间加载
if (self.tasks.count > self.max) {
[self.tasks removeObjectAtIndex:0];
[self.tasksKeys removeObjectAtIndex:0];
}
}
//MARK: 回调函数
//定义一个回调函数  一次RunLoop来一次
static void Callback(CFRunLoopObserverRef observer, CFRunLoopActivity activity, void *info){
ViewController * vc = (__bridge ViewController *)(info);
if (vc.tasks.count == 0) {
return;
}
BOOL result = NO;
while (result == NO && vc.tasks.count) {
//取出任务
RunloopBlock unit = vc.tasks.firstObject;
//执行任务
result = unit();
//干掉第一个任务
[vc.tasks removeObjectAtIndex:0];
//干掉标示
[vc.tasksKeys removeObjectAtIndex:0];
}
}
//这里面都是C语言 -- 添加一个监听者
-(void)addRunloopObserver{
//获取当前的RunLoop
CFRunLoopRef runloop = CFRunLoopGetCurrent();
//定义一个centext
CFRunLoopObserverContext context = {
0,
( __bridge void *)(self),
&CFRetain,
&CFRelease,
NULL
};
//定义一个观察者defaultModeObsever
static CFRunLoopObserverRef defaultModeObsever;
//创建观察者
defaultModeObsever = CFRunLoopObserverCreate(NULL,
kCFRunLoopBeforeWaiting,
YES,
NSIntegerMax - 999,
&Callback,
&context
);
//添加当前RunLoop的观察者
CFRunLoopAddObserver(runloop, defaultModeObsever, kCFRunLoopCommonModes);
//c语言有creat 就需要release
CFRelease(defaultModeObsever);
}
@end

 

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