大图片在渲染的时候,比较耗费时间
我们利用runloop 来优化:
思路:1.每一次runloop,都只加载一个小任物,把图片任务放到数组,从数组循环来加载.这样可以是项目达到流畅.
2.只加载当前视图内的图片任务
3.为了不让runloop休眠.我们要用一个timer区持有这个runloop 或者 通知注册runloop事件,让快要睡眠的时候去执行唤醒.
直接贴代码
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#import "dwurunloopworkdistribution.h"
#import
#define dwurunloopworkdistribution_debug 1
@interface dwurunloopworkdistribution ()
@property (nonatomic, strong) nsmutablearray *tasks;
@property (nonatomic, strong) nsmutablearray *taskskeys;
@property (nonatomic, strong) nstimer *timer;
@end
@implementation dwurunloopworkdistribution
- (void)removealltasks {
[self.tasks removeallobjects];
[self.taskskeys removeallobjects];
}
- (void)addtask:(dwurunloopworkdistributionunit)unit withkey:(id)key{
//将任务对应的添加到task 和 taskkeys数组数组中方便在注册方法中的callback中以待处理
[self.tasks addobject:unit];
[self.taskskeys addobject:key];
// nslog(@"%@%@",unit,key);
if (self.tasks.count > self.maximumqueuelength) {
[self.tasks removeobjectatindex:0];
[self.taskskeys removeobjectatindex:0];
}
}
- (void)_timerfiredmethod:(nstimer *)timer {
//we do nothing here
}
- (instancetype)init
{
if ((self = [super init])) {
_maximumqueuelength = 30;
_tasks = [nsmutablearray array];
_taskskeys = [nsmutablearray array];
// _timer = [nstimer scheduledtimerwithtimeinterval:0.1 target:self selector:@selector(_timerfiredmethod:) userinfo:nil repeats:yes];
}
return self;
}
+ (instancetype)sharedrunloopworkdistribution {
static dwurunloopworkdistribution *singleton;
static dispatch_once_t once;
dispatch_once(&once, ^{
singleton = [[dwurunloopworkdistribution alloc] init];
[self _registerrunloopworkdistributionasmainrunloopobserver:singleton];
});
return singleton;
}
+ (void)_registerrunloopworkdistributionasmainrunloopobserver:(dwurunloopworkdistribution *)runloopworkdistribution {
static cfrunloopobserverref defaultmodeobserver;
//kcfrunloopbeforewaiting runloop 进入休眠的时候唤醒
_registerobserver(kcfrunloopbeforewaiting, defaultmodeobserver, nsintegermax - 999, kcfrunloopdefaultmode, (__bridge void *)runloopworkdistribution, &_defaultmoderunloopworkdistributioncallback);
/*
1. kcfrunloopdefaultmode: 默认 mode，通常主线程在这个 mode 下运行。
2. uitrackingrunloopmode: 追踪mode，保证scrollview滑动顺畅不受其他 mode 影响。
3. uiinitializationrunloopmode: 启动程序后的过渡mode，启动完成后就不再使用。
4: gseventreceiverunloopmode: graphic相关事件的mode，通常用不到。
5: kcfrunloopcommonmodes: 占位mode，作为标记defaultmode和commonmode用。
*/
}
// 验证下 这是什么调用方法 static
static void _registerobserver(cfoptionflags activities, cfrunloopobserverref observer, cfindex order, cfstringref mode, void *info, cfrunloopobservercallback callback) {
cfrunloopref runloop = cfrunloopgetcurrent();
cfrunloopobservercontext context = {
0,
info,
&cfretain,
&cfrelease,
null
};
// switch (activities) {
// case kcfrunloopentry:
// nslog(@"即将进入runloop");
// break;
// case kcfrunloopbeforetimers:
// nslog(@"即将处理timer");
// break;
// case kcfrunloopbeforesources:
// nslog(@"即将处理input sources");
// break;
// case kcfrunloopbeforewaiting:
// nslog(@"即将睡眠");
// break;
// case kcfrunloopafterwaiting:
// nslog(@"从睡眠中唤醒，处理完唤醒源之前");
// break;
// case kcfrunloopexit:
// nslog(@"退出");
// break;
// }
observer = cfrunloopobservercreate( null,
activities,
yes,
order,
callback,
&context);
cfrunloopaddobserver(runloop, observer, mode);
//创建一个runloop观察者
/*
cfallocatorref allocator:内存分配
cfoptionflags activities :唤醒标志
boolean repeats:是否重复
cfindex order :优先级
cfrunloopobservercallback callout :回调 绑定
cfrunloopobservercontext *context :传递
*/
cfrelease(observer);
}
//typedef void (*cfrunloopobservercallback)(cfrunloopobserverref observer, cfrunloopactivity activity, void *info);
static void _runloopworkdistributioncallback(cfrunloopobserverref observer, cfrunloopactivity activity, void *info)
{ // __bridge 类型 实现id类型与void*类型
dwurunloopworkdistribution *runloopworkdistribution = (__bridge dwurunloopworkdistribution *)info;
if (runloopworkdistribution.tasks.count == 0) {
return;
}
bool result = no;
while (result == no && runloopworkdistribution.tasks.count) {
dwurunloopworkdistributionunit unit = runloopworkdistribution.tasks.firstobject;
result = unit();
[runloopworkdistribution.tasks removeobjectatindex:0];
[runloopworkdistribution.taskskeys removeobjectatindex:0];
}
}
static void _defaultmoderunloopworkdistributioncallback(cfrunloopobserverref observer, cfrunloopactivity activity, void *info) {
nslog(@"---------> callback唤醒回调 当前状态cfrunloopactivity[%lu]",activity);
//cfrunloopobserverref 观察者
//cfrunloopactivity runloop状态 kcfrunloopbeforewaiting
// 接下来执行 _runloopworkdistributioncallback
_runloopworkdistributioncallback(observer, activity, info);
// kcfrunloopentry = (1ul << 0), // 即将进入loop
// kcfrunloopbeforetimers = (1ul << 1), // 即将处理 timer
// kcfrunloopbeforesources = (1ul << 2), // 即将处理 source
// kcfrunloopbeforewaiting = (1ul << 5), // 即将进入休眠
// kcfrunloopafterwaiting = (1ul << 6), // 刚从休眠中唤醒
// kcfrunloopexit = (1ul << 7), // 即将退出loop
}
@end
@implementation uitableviewcell (dwurunloopworkdistribution)
@dynamic currentindexpath;
- (nsindexpath *)currentindexpath {
nsindexpath *indexpath = objc_getassociatedobject(self, @selector(currentindexpath));
return indexpath;
}
- (void)setcurrentindexpath:(nsindexpath *)currentindexpath {
objc_setassociatedobject(self, @selector(currentindexpath), currentindexpath, objc_association_retain_nonatomic);
//这四个后面的参数分别表示:源对象，关键字，关联的对象和一个关联策略。
}
.h 文件
#import typedef bool(^dwurunloopworkdistributionunit)(void); @interface dwurunloopworkdistribution : nsobject @property (nonatomic, assign) nsuinteger maximumqueuelength; + (instancetype)sharedrunloopworkdistribution; - (void)addtask:(dwurunloopworkdistributionunit)unit withkey:(id)key; - (void)removealltasks; @end @interface uitableviewcell (dwurunloopworkdistribution) @property (nonatomic, strong) nsindexpath *currentindexpath; @end
代码分析来源于:
推荐一个第三方runloopworkdistribution，地址https://github.com/diwu/runloopworkdistribution
我们可以添加观察者 监听runloop的循环
// 添加一个监听者
- (void)addobserver {
// 1. 创建监听者
/**
* 创建监听者
*
* @param allocator#> 分配存储空间
* @param activities#> 要监听的状态
* @param repeats#> 是否持续监听
* @param order#> 优先级, 默认为0
* @param observer 观察者
* @param activity 监听回调的当前状态
*/
cfrunloopobserverref observer = cfrunloopobservercreatewithhandler(kcfallocatordefault, kcfrunloopallactivities, yes, 0, ^(cfrunloopobserverref observer, cfrunloopactivity activity) {
/*
kcfrunloopentry = (1ul << 0), 进入工作
kcfrunloopbeforetimers = (1ul << 1), 即将处理timers事件
kcfrunloopbeforesources = (1ul << 2), 即将处理source事件
kcfrunloopbeforewaiting = (1ul << 5), 即将休眠
kcfrunloopafterwaiting = (1ul << 6), 被唤醒
kcfrunloopexit = (1ul << 7), 退出runloop
kcfrunloopallactivities = 0x0fffffffu 监听所有事件
*/
//nslog(@"%@", [nsrunloop currentrunloop].currentmode); // 查看当前的runloop运行状态
switch (activity) {
case kcfrunloopentry:
nslog(@"runloop--进入");
break;
case kcfrunloopbeforetimers:
nslog(@"runloop--timer事件");
break;
case kcfrunloopbeforesources:
nslog(@"runloop--source事件");
break;
case kcfrunloopbeforewaiting:
nslog(@"runloop--休眠");
break;
case kcfrunloopafterwaiting:
nslog(@"runloop--唤醒");
break;
case kcfrunloopexit:
nslog(@"runloop--退出");
break;
default:
break;
}
});
// 2. 添加监听者
/**
* 给指定的runloop添加监听者
*
* @param rl#> 要添加监听者的runloop
* @param observer#> 监听者对象
* @param mode#> runloop的运行模式, 填写默认模式即可
*/
cfrunloopaddobserver(cfrunloopgetcurrent(), observer, kcfrunloopdefaultmode);
}
- (void)viewdidload {
[super viewdidload];
[self addobserver]; // 添加监听者
}
看log
正常的runloop 是 睡眠 唤醒 一个循环结束
我们他runloop不休眠 一直在即将睡眠的时候唤醒
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