NSTimer
1. iOS 10 NSTimer 的新 API
iOS 10 之后，苹果为 NSTimer 添加了一个官方 API，支持传入 block 类型参数。
+ (NSTimer *)timerWithTimeInterval:(NSTimeInterval)interval
repeats:(BOOL)repeats
block:(void (^)(NSTimer *timer))block
API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));
+ (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)interval
repeats:(BOOL)repeats
block:(void (^)(NSTimer *timer))block
API_AVAILABLE(macosx(10.12), ios(10.0), watchos(3.0), tvos(10.0));
2. iOS 10之前，防止对 VC 的循环引用方案
- 给 NSTimer 添加一个 category，新增传入 block 类型参数的接口
- 分类实现是将此 block 作为 NSTimer 的 userInfo参数传入，而 NSTimer 的 target 则设置为 timer 自己。以此来避免 NSTimer 持有 VC
// NSTimer+BlocksSupport.h
#import <Foundation/Foundation.h>
@interface NSTimer (BlocksSupport)
+ (NSTimer *)ly_scheduledTimerWithTimeInterval:(NSTimeInterval)interval
repeats:(BOOL)repeats
block:(void(^)())block;
@end
// NSTimer+BlocksSupport.m
#import "NSTimer+BlocksSupport.h"
@implementation NSTimer (BlocksSupport)
+ (NSTimer *)ly_scheduledTimerWithTimeInterval:(NSTimeInterval)interval
repeats:(BOOL)repeats
block:(void(^)())block {
return [self scheduledTimerWithTimeInterval:interval
target:self
selector:@selector(ly_blockInvoke:)
userInfo:[block copy]
repeats:repeats];
}
+ (void)ly_blockInvoke:(NSTimer *)timer {
void (^block)() = timer.userInfo;
if(block) {
block();
}
}
@end
