-(NSMutableArray *)sortArrayByProminent:(NSArray *)arrayObject
{
NSArray * array = [arrayObject sortedArrayUsingComparator:^(id obj1, id obj2) {
Business * objj1=obj1;
Business * objj2=obj2;
NSUInteger prom1=[objj1 .prominent intValue];
NSUInteger prom2=[objj2 .prominent intValue];
if (prom1 > prom2) {
return NSOrderedAscending;
}
if (prom1 < prom2) {
return NSOrderedDescending;
}
return NSOrderedSame;
}];
NSMutableArray *arrayHasBeenSorted = [NSMutableArray arrayWithArray:array];
return arrayHasBeenSorted;
}
所以基本上我有这个 block 用于对数组进行排序。
现在我想编写一个返回该 block 的方法。
我该怎么做?
我试过了
+ (NSComparator)(^)(id obj1, id obj2)
{
(NSComparator)(^ block)(id obj1, id obj2) = {...}
return block;
}
我们就说它还行不通吧。
最佳答案
像这样返回一个 block 的方法签名应该是
+(NSInteger (^)(id, id))comparitorBlock {
....
}
这分解为:
+(NSInteger (^)(id, id))comparitorBlock;
^^ ^ ^ ^ ^ ^ ^
ab c d e e b f
a = Static Method
b = Return type parenthesis for the method[just like +(void)...]
c = Return type of the block
d = Indicates this is a block (no need for block names, it's just a type, not an instance)
e = Set of parameters, again no names needed
f = Name of method to call to obtain said block
更新:在您的特定情况下,NSComparator
已经是 block 类型。它的定义是:
typedef NSComparisonResult (^NSComparator)(id obj1, id obj2);
因此,您需要做的就是返回此 typedef:
+ (NSComparator)comparator {
....
}
关于objective-c - 如何创建一个返回 block 的 objective-c 方法,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/13193673/