NSPredicate(谓词的基本使用)

熟悉NSPredicate

NSArray *array = [NSArray arrayWithObjects:@"beijing", @"shanghai", @"guangzhou", @"wuhan", nil];
//在数组里面筛选含有@"be"的字符串
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@", @"an"];
NSArray *tempArray = [array filteredArrayUsingPredicate:predicate];
[tempArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
     NSLog(@"tempArray_obj = %@", obj);
}];
    
/***************************************************************/
//NSPredicate给我留下最深印象的是两个数组求交集的一个需求，如果按照一般写法，需要2个遍历，但NSArray提供了一个filterUsingPredicate的方法，用了NSPredicate，就可以不用遍历！
NSArray *array1 = [NSArray arrayWithObjects:@1,@2,@3,@5,@6,@7, nil];
NSArray *array2 = [NSArray arrayWithObjects:@4,@5,@6, nil];
    
NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"SELF in %@", array2];
NSArray *temp = [array1 filteredArrayUsingPredicate:predicate1];
    
[temp enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
     NSLog(@"temp_obj = %@", obj);
}];

NSPredicate的比较功能

/*
     比较运算符>,<,==,>=,<=,!=
     可用于数值及字符串
     例：@"number > 100"
     */
NSArray *array = [NSArray arrayWithObjects:@1,@2,@3,@4,@5,@6, nil];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF >= 4"];
NSArray *filterArray = [array filteredArrayUsingPredicate:predicate];
[filterArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    NSLog(@"filterArray_obj = %@", obj);
}];

Predicate范围运算功能

/*
     范围运算符：IN、BETWEEN
     例：@"number BETWEEN {1,5}"
     @"address IN {'shanghai','beijing'}"
     */
NSArray *array = [NSArray arrayWithObjects:@1,@2,@3,@4,@5,@2,@6, nil];
//NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF in {2,5}"];
//"in"是找到数组中2和5两个元素
//"BETWEEN"是找到数组中2到5之间的元素
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF BETWEEN {2,5}"];
NSArray *rangeArray = [array filteredArrayUsingPredicate:predicate];
[rangeArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    NSLog(@"rangeArray_obj = %@", obj);
}];

与自身相比的功能

/*
     字符串本身:SELF
     例：@“SELF == ‘APPLE’"
     */
NSArray *placeArray = [NSArray arrayWithObjects:@"Shanghai",@"Hangzhou",@"Beijing",@"Macao",@"Taishan", nil];
NSPredicate *predicatre = [NSPredicate predicateWithFormat:@"SELF == 'Beijing'"];
NSArray *selfArray = [placeArray filteredArrayUsingPredicate:predicatre];
[selfArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    NSLog(@"selfArray_obj = %@", obj);
}];

字符串相关：BEGINSWITH、ENDSWITH、CONTAINS

/*
     字符串相关：BEGINSWITH、ENDSWITH、CONTAINS
     例：@"SELF CONTAIN[cd] 'ang'"   //包含某个字符串
     @"SELF BEGINSWITH[c] 'sh'"     //以某个字符串开头
     @"SELF ENDSWITH[d] 'ang'"      //以某个字符串结束
     注:[c]不区分大小写[d]不区分发音符号即没有重音符号[cd]既不区分大小写，也不区分发音符号。
     */
NSArray *placeArray = [NSArray arrayWithObjects:@"Shanghai",@"Hangzhou",@"Beijing",@"Macao",@"Taishan", nil];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF CONTAINS [cd] 'an'"];
NSArray *relateArray = [placeArray filteredArrayUsingPredicate:predicate];
[relateArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    NSLog(@"relateArray_obj = %@", obj);
}];

Predicate 的通配

/*
     通配符：LIKE
     例：@"name LIKE[cd] '*er*'"
     //  *代表通配符,Like也接受[cd].
     @"name LIKE[cd] '???er*'"
     */
NSArray *placeArray = [NSArray arrayWithObjects:@"Shanghai",@"Hangzhou",@"Beijing",@"Macao",@"Taishan", nil];
NSPredicate *pradicate = [NSPredicate predicateWithFormat:@"SELF LIKE '*an*'"];
NSArray *cardArray = [placeArray filteredArrayUsingPredicate:pradicate];
[cardArray enumerateObjectsUsingBlock:^(id  _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
    NSLog(@"cardArray_obj = %@", obj);
}];